A person (usually female) who becomes a hassle and general embarrassment when drunk. However, they are harmless and cause more laughter/ stories/ material for blackmail than utter humiliation and upset for their minders (usually male).
She was such a liability she tried to take her clothes off.
You're a fcuking liability
see also: saviour
Read between the lines: It's like giving them the finger, but you've got the liability...