IMO, you can't fake being funny. He can't fake saying something you find funny. You either think it's funny and you laugh, or you dont't laugh and you think, "what a doofus!" I remember the first rather snide joke my T made in session - I was like, yeah, okay, I can work with this guy!
ETA: my previous t/pdoc often asked me, why are you always trying to make me laugh? I recently realized it was an act of desperation, an act I put on for my family. now I feel like i'm doing more listening, more feeling, more caring, less joking.