Last night, Katy Perry appeared on”The Simpsons” as a real person, not a jaundice cartoon. The live-action show full of Springfield puppets had a premise, but it was inconsequential considering Katy had a tight, red latex dress stretched over her curves. It was all a burn on “Sesame Street” for banning her too sexy for TV duet with Elmo. Mr. Burns got a face full of glorious cleavage, and then during the credits, Moe got a face full of crotch. Nicely done, “Simpsons” writers. I hope you built the entire story around Moe going down on Katy.