To feel nervous; to feel threatened and vulnerable and alive and engaged in that sense when interacting with someone you're really attracted to? I think that's wonderful. That's usually the best part. In fact, it's almost always downhill from there.
A very beautiful young woman once asked me to sign her breasts. That was back when I was a hip young thing - it's been all downhill since then.
The minute I get a big head and start acting like the big man on campus, it's all downhill from there.