Both plots in this episode are really great, all the jokes with peter and his "prostate ex am" or "rape" as he calls it were great, along with Stewie's "I love my mummy" plot. Some of my favourite jokes in the episode include, when Stewie is at the park with the "unfamiliar dog" and his fantasy about rupert and him at the beach.
Another great scene was in the courtroom, I think it's just so funny how Peter convinces the judge to favour in his behalf by saying: "Don't you remember your last prostate exam" as all grainy, and black and white?" XD.
This is probably one of the best episodes, since the shows return and I believe it could've been passed off as a episode from season 1-3.