make a monkey of someone

make a monkey (out) of (someone or oneself)

To do something that makes someone (or oneself) seem stupid or ridiculous. I know Greg is only trying to impress Lisa, but he's making a monkey out of himself by telling so many corny jokes. I'm not going to dance too much at the party because I don't want to make a monkey out of myself in front of my coworkers.
See also: make, monkey, of

make a monkey of (or out of) someone

humiliate someone by making them appear ridiculous.
See also: make, monkey, of, someone