Why does it feel extra good after being able to be of help to someone of the opposite sex?
- Is it due to pureness of one’s heart?
- Is it because of a fulfilled ego?
- Is it because of a chance for a thrilling romantic tryst?
- 2 & 3.
According to me, all of the above have some sort of evolutionary underpinnings (contributes to the propagation of the human species in general) but any other explanation would be most welcome!
Brown in the Land of Blues and Blondes 
5. Is it because a smile from opposite sex feels better than from the same sex?I hope you don’t base your Nobel-winning study on these thesis, LOL!
@Smek: no wonder da vinci couldn’t finish his painting. he started wanking off after finishing mona lisa’s smile. he forgot about her eyebrows in the end. LOL!
And I thought he was looking at himself in a mirror all along, doing what you described. Art starts making sense 🙂