[Death by Mirrors]

Yeah, you can name any food. It goes like, example: at one time the beast will eat all things that are yellow, or all things that have seven letters, or all things that... whatever. It will refuse things which do not meet the secret criteria. So through offering lots of food you either try to figure out what the beast wants, or name as much food as you can think of (each in its own post and waiting for other people to play inbetween), hoping a few will be successful.

Also 5 and 7 are primes too ;)