Sleazeboy
A sleazboy is a smooth taking, barfly and nightlife junkie extrovert who always knows where the party is at, who the easy girls are and how to to queue jump and be on guest list at all the nightclubs. An operator who always know where the free score is. It can be used as term of endearment in certain circles.

Possibly derived from the Irvine Welsh Novel Trainspotting where the characters names had the suffix -boy i.e. Rentboy, Sickboy as is common with nicknames in inner city Scotland.
That smug looking sleazeboy over there at the bar, was the one who slept with my girlfriend's sister in the club toilets.