Basically a form of gambling that goes on in every large and small office around the country. Although discouraged in some of your larger corporations, both law enforcement and the corporations themselves usually turn a blind eye towards the conduct of an office pool.

Usually centered around a large sporting event such as the Super Bowl, World Series games, play-off games involving your local team of choice, or college bowl games, unless you happen to live in Columbus, Ohio, home of the Ohio State Buckeyes, where pools are run every week during football season. Not strictly limited to the office, local taverns, where the stakes are usually considerably higher, have been known to run a pool or two of their own.

Equipment needed:

Pen or Pencil or Crayon or Marker
Paper
Copier - usually for office pool use only

Rules

A sheet of paper is divided into 100 "boxes"
10 vertically - representing the "home " team
10 horizontally -representing the "away" team

Each individual wishing to participate in the pool contributes a specified dollar amount needed to purchase a "box". The normal pool runs between $1.00 and $5.00 per box. Bars are usually higher. Upon purchase of said box, the individual is allowed to pick a box from among the 100 and writes either their name or some other alias. There's no limit on the amount of boxes an individual may purchase.

When each of the 100 boxes are filled, the number 0-9 are written on small pieces of paper and placed in a receptacle, such as a hat. The person running the pool then draws the numbers at random for the vertical or home team, each number corresponding to one of the boxes. The process is then repeated for the horizontal or away team.

The Play - in its simplest form

Let's assume that each box cost $1.00. This would make the total pool $100.00
Football, as every god fearing American knows, is broken down into 4 quarters.
The pool is then going to make 4 pay-offs of $25.00 each to winner of each quarter

How to Win

Its actually pure luck, there's no skill involved and one needs to know little or nothing about the sport being played in order to win. Luck of the draw is all that's involved.
Okay, you've paid your money and placed your name in a box. Numbers have been drawn and you get two of them,. one for the home team and one for the away team. Let's for instance say your numbers are 7 for the home team and 0 for the away team.

Game time comes, the home team scores a touchdown and makes the extra point - yeah! - 7 points for the good guys!!! The away team goes scoreless during the first quarter.
Score at the end of the first quarter:
Home - 7
Away -0
Congratulations, you've just won yourself 25 bucks!!!
The process is then repeated for each of the 3 quarters. There's usually some debate as to the fourth quarter. What if the game ends tied and goes to overtime? Not to worry, there's usually a specification at the beginning of the pool on whether it will end in the fourth quarter or if the final score will determine the outcome.

That's it in its simplest form. There are plenty of other derivations such as reverse scores and the like that increase the chances of winning back some of your money.

Note: Its estimated that all of the money wagered in office/bar pools easily surpasses the amount that is legally wagered in Las Vegas on the Super Bowl