I'm only sexually attracted to my boyfriend when he dresses like a hamster

Terrance
Last halloween me and my boyfriend went as alvin and The chipmunks... We got bak to my house that night, and had the best sex ever... Now i really don't find him attractive unless he I think of him in his little hamster outfit.
How do i bring this up to him? I feel silly, but i think i can only continue to date him if he wears his costume.
Help plz!