v.1. To consume alcoholic beverages steadily: They were boozing up all night and didn't come home until sunrise.
2. To serve someone enough alcohol to cause drunkenness: The sales representative was well known for boozing up her clients after a sale. He doesn't seem friendly, but he's more sociable if you booze him up a bit.
3. To become drunk. Used in the passive: I was too boozed up to drive home.