She has to be trolling us with that shirt. There's no way someone who is always sucking on her teeth is an actual Dr. Teeth fan.
Actually, I think that's one of the exclusive D23 shirts that was released for Muppets Mayhem, so of course Tim had to buy it. He's all about the exclusive shirts. It's not flattering on Jenn, but I actually think that color would look even worse on Tim.