To get
drunk or start drinking before the hang over from last
night has worn off.
Thus having something to "tie onto"
To tie one drinking
session to another before the effects/consequences of the last have expired.
Guy 1: Hey, what's going on there?
Guy 2: I'm hungover as fuck, they had
quarter pitcher
night at Jake's last
night.
Guy 1: So you're just going to hang out?
Guy 2: Fuck it lets tie one on.
Guy 1&2: *Crack open beers and commence drinking*