When you take a massive grommer in someone's toilet and close the lid afterwards while they are away on vacation. Then they come home after a long drive, rush to the toilet, open the seat and BOOM they meet the house sitter.
Did you hear that Amos threw up blood when he met his house sitter after he got back from the beach yesterday?
Great genitalia trick to be done while sitting down. This is accomplished when you sneak part of your sack out of your fly and hold it to the chair your sitting in. Then rise as much as you can while saying "awww man, looks like I sat in some gum."
Rebecca saw bill's nuts while he was doing the "gum sitter" for a couple of buddies.
Refers to the idiots who instantly merge into the fast lane as soon as they get on the highway. They proceede to drive under the speed limit as to piss off the people who want to go faster then them as if they will win a trophy for slowing down as many people as they possibly can. When the oportunity comes to merge into the middle lane they "sit" and wait till the person behind them trys to pass and then move over just to get in front of them again, sometimes causing accidents and making a lot of people mad.
Damn, Im late for work and it seems as if everyone is a left lane sitter today.