Why cant he stop it when he knows its makes me upset?

I was with a guy like that, every time we talked about a celebrity he said she was y or referred to some other who was. Hes insecure and trying to wind you up. Maybe you should agree with him and see how he reacts and show it doesnt bother you or else start mentioning guys or friends of his who are and go into explicit details about how attractive they are and how big they are.