The answer to the riddle is "Pressure" because it fits all the given clues. Pressure can turn polar bears white (due to stress), make people cry (when feeling overwhelmed), make guys have to pee (pressure on the bladder), make girls comb their hair (feeling pressure to look good), make celebrities look stupid (pressure from the media), make normal people look like celebrities (pressure to conform to societal standards), turn pancakes brown (pressure from cooking), make champagne bubble (pressure inside the bottle), pop when squeezed (increase in pressure), and make someone pop when looked at (feeling intense pressure).