Don Juannabe

Refers to one of the increasingly large group of males who assume that, like the famous Don Juan, they can seduce any woman, anytime, regardless of the fact that most women avoid them like the plague after the first 5 minutes of talking.

Also spelled "Don Wannabe" for those without the Latin flavour.

Guy: Man I hate Bob, he's such a Don Juannabe.
Other guy: Yeah, he's always hitting on my girlfriend, what a douche/moron/maroon.