This is easily one of my favourite riddles as the answer is quite obvious and doesnt require the agonising contortion of your brain cells to work it out. I am sure some of you have seen it before, but if not, lets test some of you

 

I turn polar bears white,

and I will make you cry.

I make guys have to pee,

and girls comb their hair.

I make celebrities look stupid,

and normal people look like celebrities.

I turn pancakes brown,

and make your champagne bubble.

If you squeeze me, I'll pop.

If you look at me, you'll pop.

What am I?

I love this one too. The version I know ends with "Can you guess the riddle?"...

pressure

it must be pressure???