Men, Can You Explain?

I've often considered this to be one of the great mysteries of the universe. Why do men get such a thrill from women swallowing when they give oral? Every since I saw my first porn flick in that dark theater with my friend (she made me go see it!) I've had that question on my mind.

I'm writing a story, and was doing some research on different techniques, when this recurring theme stayed on the surface. I've asked men about this before, but I never got a real answer, well, at least not one that made sense to me. I can surely understand the thrill in receiving a blow job,and there's a lot of thrill in giving one. But the swallowing part, I never could get the complete understanding of why that was such a turn-on to watch. So men, please post your pleasure on the poll to the right. And feel free to drop me an email or leave a comment if you have a really GOOD explanation of why you find swallowing so appealing. I just need to know!