W/O the "can you guess the riddle" part, I'd say the answer is a thought.
Polar bear's hair is actully translucent. So it's just your thought that makes polar bears white.
Sad thougths can make you cry.
Your body signals when it's time to pee, but you have to decide to go to bathroom.
A girl's thought that her hair's unkempt can make her comb her hair.
Celebrities with little thoughts can look stupid.
A normal person with singular thoughts can become and look like celebrities.
Your wanting your pancakes brown will make them brown.
It's men's thought that created bubbly champagne.
If you repress a thought, it might disappear or pop in the figurative sense.
An antipathy can make you go ballistic or pop in the figurative sense.