Jonah Hill is an American actor who has starred in films like Superbad, The Wolf of Wall Street and 21 Jump Street.
In the episode Baby Daddy, Malloy tells Ethel that he put her picture and Steve's picture into a computer program to determine what their child will look like, and so he shows her Jonah Hill's face. So what does Ethel do? Scream out a big "Noooo".