An odd translation request

Odd translation request but if you could it'd be a great help. We've got an in-joke betwenn my friends and I about one of said friends' old Facebook profile picture made him look like a happy child molester. I now want to make that into a t-shirt slogan along with the photo for when we go on holidays. Obviously it'd look strange to have a t-shirt with "Happy Molester" blazoned across the top so I'd like to know what "The Happy Molester" is as Gaeilge so it could be more discrete. I assume it's An _____ Athasach" or something like that

I have a decent standard of Irish but never came across the word in my studies so it'd be a great help.