The idea of a Monopoly Pub Crawl - played in London, naturally - is to, in a single day, visit and drink at each of the 26 locations (22 properties and 4 stations) appearing on the UK version of the Monopoly Board.
This is NOT as easy as it sounds.
I was part of a team which successfully did this on August 12, 2006, however, so I think I can offer a little advice.
Throw away your Monopoly board.
Leave your Chance cards and oversized novelty Monopoly dog/car/boot/iron/thimble/battleship pieces at home. Take off your stupid bunny ears and abandon all your notions of forfeits, dares, and crazy additional rules. This is a twenty-six-pub crawl. It is not a game of Monopoly. You do not have time to muck about with dice.
Visiting the properties in the order they appear on the board is torturous, and only becomes slightly easier if you discard the four stations. Better is to use the optimal ordering described here. Print the thing out and nominate a reliable member of your party to act as Routemaster, i.e. read it and keep you all on course. If some members of your party have arranged to do a swift reconnaissance run on an earlier day, or even completed a full crawl, this will help immeasurably. A London A-Z may also help.
Ideally you should start as early in the morning as possible - in practice, a 10am start at Elephant & Castle tube station gives you a decent shot at reaching the finish at Oxford Street before 11pm. Visiting 26 different pubs in this period gives you an average of 30 minutes per pub, including travel time. Therefore you can't dawdle. Nominate another trustworthy individual to act as Timekeeper - allow yourselves 15 minutes' drinking time per pub and you should stay on course, although travel times will obviously vary uncontrollably.
What to bring
This is a LONG day - more than 12 hours' alternating drinking and walking. Therefore, travel light. Wear comfortable shoes and avoid bringing much more than the necessary, which is a 1-Day Off-Peak London Travelcard for Zones 1 and 2 (this is good for all buses and tube trains, which you'll be making extensive use of) OR an Oyster card (same), plus approximately £60 in cash, or enough money to purchase 26 half-pints of beer and two fast food meals. (A pint (~2 units) at each pub works out to be very expensive and suicidally difficult even WITHOUT the time constraints involved - a half-pint (or, equivalently, a single shot of some spirit with a stimulating mixer) at each location is a much more plausible target.) Naturally, unless you are strong of stomach, you will probably end up skipping drinks sooner or later. It is generally considered preferable to skip drinks in order to make it to the finish on time than to slow down or drop out completely due to drunkenness.
You can bring water, but remember you can get free water at any pub. Learn to create a siphon with a drinking straw; this makes topping your bottle up easier.
While you might not be able to plan early enough to get this right, ideal weather for a Monopoly Crawl is a breezy cool summer's day. You will be walking during the hottest part of the day and finishing relatively early at night, so too much heat will just make it impossible to move. Whatever the case, wear as little as you can get away with based on the weather forecast as you'll get pretty warm and tired whatever happens.
Your party can theoretically be any size, but in practice four people is pretty much the minimum and more than ten people will have difficulty fitting into many of the later pubs, because as time goes on the pubs and streets will get increasingly crowded, particularly if you do this on a Friday or Saturday night (we did Saturday). While it may seem a little paranoid and unnecessary, during the later stages a surreptitious head count after every pub will probably prove helpful to avoid leaving people behind if they e.g. nip to the toilet just before you all leave (and you will all be paying many visits to many not-particularly-nice toilets, have no doubt about that). Luckily, with mobile phones it's easy for those left behind to catch up these days.
On a more tactical note, ordering drinks in each pub is a time-consuming prospect even with no queue. Ordering one drink each is preposterous, as anybody who has spent ANY amount of time in a British pub will attest, whereas one person ordering solo for everybody at once requires immense powers of memory and too many arms. Best practice is to divide your group up into autonomous groups of three or four people each - these can then handle the ordering of each round of drinks individually. While each pub's designated orderer "gets them in", the rest of you can swiftly nab seats.
The best way is to group the heavy drinkers together and the lighter drinkers together; this way, people who intend to skip pubs do not end up buying substantially more beer than they drink.
Several of the pubs you'll visit, particularly the early ones, will be used to Monopoly pub crawlers. If you do your crawl on a weekend there is also a decent chance that you'll encounter at least one other group doing exactly the same thing as you. Use your best judgement when dealing with these people as you may end up matching pace and tailing them or being tailed for the bulk of the crawl.
It is not recommended to embark on this crawl unless you are a reasonably experienced drinker. Know your own limits; recognise the signs that you are reaching them; react accordingly. If it's summer, the dehydrating effect of alcohol may be exacerpated by heat and sun. If you have never drunk to excess before, this is not the day to start - central London on a Saturday night is not a forgiving, consequence-free environment.
At any given pub you will obviously have a choice of beverages available. It's strongly advised to select beers you are familiar with. Today is not the day to experiment with new beers; an unexpectedly foul-tasting ale (of which there are many) may throw your whole game off.
This is NOT a tourist tour of London. Many of the stops on the route are very unremarkable locations indeed and while you will fleetingly pass a few landmarks such as Trafalgar Square you'll have time for maybe a few seconds to go "ooh, Trafalgar Square" before it's "hurry, we're late for the next pub!" And during the last stages of the crawl you will find everything really begins to blur together, even as you stumble along the entire length of Oxford Street. You will see a good amount of London, but it's a pretty strange subset of London. Like most pub crawls, drinking is the aim of the game.
Even so: it is a good idea to bring cameras, for the taking of pictures, and we found it to be extremely amusing to carry around a notepad and pencil, for the taking of notes, as amusing larks will most assuredly be had en route, and you will NOT remember even half of them if you're doing it right. You will also need a notepad if you wish to record 1) who wins (finishes their drink first) at each pub, 2) who loses (finishes last or not at all) at each pub, and 3) who drops out and when, which are all interesting statistics to look over later.
A hearty breakfast is essential, preferably NOT eaten immediately before you start in the morning. You will be eating lunch and dinner on the move - there are loads of fast food places on the route - we stopped at Burger King in Marylebone Station and at a pizza cart in Leicester Square respectively. Do not expect to have time for a full, nourishing meal anywhere on the route, however. You'll be surviving this crawl mostly on alcohol, adrenaline, and, if you're like me, also caffeine, taurine and snacks. You can catch up on your five-a-day tomorrow.
Some final notes
Overall this is a pretty difficult challenge regardless of how tough a drinker you think you might be, so don't feel demoralised if you personally find yourself losing steam halfway through. Take a few pubs off to recuperate and you should have time to work most of the bad stuff out of your system, and maybe even come back for an enthusiastic finish. Getting to the end, regardless of how much you drink, is quite an achievement. Linger at the final pub on Oxford Street to savour the moment, and take lots of photographs.
The old adage, "Drink through it" has never applied more strongly.
If you are insane, and this will undoubtedly be the case for some of your party, you may discover come the end of your adventure that it's not yet midnight, and that the night is still young. In that case you can go clubbing. Failing that, you're now just a few steps from Tottenham Court Road tube station. You do have a ticket home, right?
Best of luck!