When someone scores a goal in hockey and puts in the top of net, it goes "top shelf". See also: top cookie
HOLY MAKINAW! He put that top shelf, right next to where mama keeps the peanut butter!
Derivation: night cap
When the bar is closing and you gather all your people together and head to one of their houses to keep drinking and mess the place up, that is a capper. Also known as an after-party.
Q: Hey man, where's the capper at?
A: I dunno man, I think Dave's, he's got booze.