Mac Daddy
From The Big Bang Theory Wiki
Sheldon tells Leonard that compared to the other three guys in that car with Penny, he is a 'veritable Mac Daddy'.
A 'Mac Daddy' is a street term for a man who has a way with women or who is particularly cool. The term 'mack' is actually derived from French ('maqereau') by way of Creole and means 'pimp'.
It's a bit odd that Sheldon uses this kind of a phrase, when he knows absolutely nothing about popular culture (0113). The use of the term at the same time that Howard is singing a song by Mac Davis is almost certainly a coincidence.
