If I had to guess anything other than "no". I'd say air or wind or something of the likes, and I'll explain.
I turn polar bears white (they have translucent hollow hairs filled with air, giving the illusion of white color when light reflects off it)
and I will make you cry. (try sticking your head out the window of a moving car and letting the wind hit you in the eyes, they'll water)
I make guys have to pee (wind makes air cold, cold weather makes us have to piss)
and girls comb their hair. (windblown hair looks mussy and often stupid, of course they'll comb it)
I make celebrities look stupid (same reason as above)
and normal people look like celebrities. (well, if we all look stupid... pretty self explanitory).
I turn pancakes brown (let just about any food product sit out in the air, and it will more than likely turn brown).
and make your champane bubble. (obviously)
If you sqeeze me, I'll pop. (air inside of balloons, etc.)
If you look at me, you'll pop. (only way you can really "see" air is by looking at the atmosphere from outter space. the vaccum will literally make you pop and die).
Can you guess the riddle? (obviously I thought the answer was "yes" as opposed to "no", being that it didn't ask whether you KNEW the answer, only whether you could GUESS what it was, and anybody can take a guess at about anything, so... yeah. Though I did try to provide some kind of logical answer just for my own amusement lol