Occasionally a clown will randomly spawn during the circus level.
After tapping on the clown he will separate revealing that 'he' is in fact two twin brothers. You have to make sure both of them use the toilet and make it to the exit without getting involved in a fight.
This is more of a pain than the other trophies requiring you to serve a unique character but still very doable provided you pay close attention to them while they are on screen.