The pit rat is one of the indigenous species of the greater boston area. They can be found in many places throughout the boston area, however they always return to their homeland, which is known as "the pit" at harvard square T station in Cambridge. This is where they spend the largest portion of their time, and where the center of their primitive society exists.
Pit rats are naturally scavengers. While they may, from time to time, seek employment, and rarely may even aquire employment, this state never lasts long. They spend most of their time smoking pot and using various and sundry other recreational drugs. Some have been known to sell drugs for money, however, as a group, they have a reputation for charging very high prices for very low quality drugs. They are the origin of the term "harvard square bag".
While some pit rats have been known to go as far as sleeping in the pit and making it their home, many do find other places to stay. Many pit rats are technically homeless (even if homeless just means "I refuse to go back to my parents house in newton"). A large subset of the pit rats have developed a system known to some as the "Pit rat infestation".
Infestation begins when a pit rat finds an old friend or a friend of a friend who has an extra bedroom or can otherwise take them in. They then procede to move in. At this point they cease to ever come home or sleep alone. One or two of their friends will stay with them all the time, effectively moving in with them. They apear to exhibit a "rotation" where every other week or so the set of friends will change, presumably as the old set has moved to another nest.
Pit rats in the situation of being the "offical" roomate then go into a mode of doing a cursory job search. They have been known to refer to being actors in independant films as "a job" or "work" even after having it pointed out that "its not a job if your not getting paid".
More research is being done on this fascinating and poorly documented species. If you choose to observe them in the wild, do be wary. Some of them can be territorial (especially ones that actually live in the pit, usually the outcasts that other pit rats don't even like and thus can't get into infestation nests). When in the pit, try not to make direct eye contact, and refrain from any sort of buisness transactions. Do not under any circumstances take a pit rat home with you, they are not safe pets and will cause infestations which are occasionally hard to get rid of.