Okay, as an adult (well, young adult) I harbor a secret love... Pokémon.
My nephew LOVES the games, he plays them all the time, and I have to admit that I play them too now

They're really addictive! He plastered my wheelchair in Pokémon stickers, and I secretly don't mind. I think I spent an hour this morning taking Pokémon quizzes. He's gotten me completely hooked on his Gameboy Pokémon games.
...Kinda sad
So what about you guys? Everyone has a guilty pleasure!