The process of going out with a group of people to a bar and hitting up each bar on the way to a certain destination (home, party, etc.) In this process you neglect how shitfaced you actually get, and don't care if you're blowing a .2 (over three times the legal limit) on a brethalyzer test, you're just out to have a good time with your bros.
It can also be explained mathematically. Let the first bar represented by A, and the final destination by B. There are 5 bars between A and B, you have to hit up each bar within a period of now until 2 am. So to solve this equation, you have to know the variable x, which represents how much fun you want to have.
Guy 1: (to the rest of his bros.) Alright so we'll start our beer crawl here at the party, move on to Chappy's, then we'll go to Dave's, get to Bill's, then we'll probably close off at The Dock, and go out for a meal somewhere along the way to my house.
Everyone in the room: Yeah!
ITT: No one really cares where you're going, or how you're getting there. We just want beer!