backpack race 

When someone is drinking beer/alcohol/etc, and someone else jumps on their back like a backpack and forces them to chug the beer. Usually done with two people at a time. Whoever gets the beer down first is the winner. The beer guzzler usually goes insane.

Kristen totally beat Kelly at the backpack race last night. Tubby lost his mind he drank so fast.

backpack race by MMjr May 26, 2008