Warning, this question contains explicit details!

Many of my friends and I, have been doing great deal of research, and none of us can find the answer to this question, so I've decided to just put it out there.

After performing fellatio, and the male ejaculates in one's mouth, why do one's lips...

tingle?

This doesn't always happen, and it mostly always happens when one's lips are exposed to cold temperatures. When it does happen, it's a very intense sensation. Is it caused from the friction, or some sort of chemical reaction?
None of us are complaining about it, because it's great, but it has confused us for some time.
If anyone knows why this takes place can they Please provide us with some answers, and a reliable source.
Thanks,
~Tiffany~

But do not forget that male cum is full of endorphins that can bind to certain receptors on your lip, and receptor binding is always stroger in lower temperature.

Sorry girls but i have never heard of this. I tried researching it but nothing came up.
What i can gather from it is that when you do it, maybe you get pins and needles or something in your lips from the constant friction. I dont see the need to worry or anything but if you start getting sore throats or cold sores around and in your mouth then id head to the doctors. But ive never heard of this happening, sorry i couldnt help

Here's my hypothesis:
Tingling (paresthesia) is caused by inadvertent pressure placed on a superficial nerve. The sensation gradually goes away once the pressure is relieved. Since the lips are made up of skin and nerves (trigeminal nerve),the pressure applied to the lips during fellatio can therefore cause paresthesia giving you that tingling sensation. Et voila!
I don't think that there is any link to ejaculate, but maybe cold temperatures can provoke paresthesia faster because lips are possibly more sensitive to change in temperatures.
I based this hypothesis by information I found on:
http://www.wikipedia.org/
I looked up the words: tingling, nerves, lips

Thanks Zorbot, that's a great hypothesis!

It's so weird, I noticed it one day, while walking home, after a booty call it was the strangest thing I had ever felt. It's a big joke between my friends and I, and by the way locoluna, we are not worried, it's fantastic, we just wanted to know the scientific reasoning behind it.
But thanks for the concern.

~Tiffany~

Because your lips have gone numb from the pressure. It is kind of like when your arm goes to sleep and is waking up.