He can be rich or poor, educated or not, vulgar or polite, handsome or not, but what characterizes this guy is his way with words and his garrulousness. More importante, he is notorious for making a pass at almost any woman. Whether or not he succeeds is irrelevant.
I'm not looking for lists. Just the best slang word or phrase for this type of person.
I'm not looking for medical terms.
I'm not looking for old-usage such as "a Don Juan."
chat up (verb) -to talk flirtatiously to (a person), esp with the intention of seducing him or her. http://www.thefreedictionary.com/chat+up
EDIT - (context where I would use it)
- Jim has been dancing with my sister all evening. Do you think he is a nice guy?
- Er... perhaps I shouldn't tell you this but when we were in College he was notorious for making passes at almost any girl. As a matter of fact he was a .................