When 4 people have sexual relations.

No fun at all, nuh uh. No sex, just some flirting. =). Is that even the least bit fun? No.

A gathering of people at someone's place with the purpose of getting drunk before going to bars or clubs. This makes getting drunk cheaper, and is therefore most common in places where alcohol is expensive. Not to be mixed with sexual encounter, though that is how these nights often end

The definition that you absolutely do NOT want to read while eating dinner and wearing sweat pants...