I'm vascular as hell, especially in my shoulders and arms, but nowhere near that.
I make a conscious effort that every time I go on a date with a girl for the first time or whatever, I try to make sure I'm covered up, as it does repel the women as fast as Vince Goodrum does having bewbies bigger than the girl I'm approaching.
It's a genetic thing to some degree (especially in my case), low body fat and also if you pose a lot or tense your muscles at work (I do a lot of gripping and have an extremely active gig) or while you're working out.