secret sixpack

A guy who has the potential of having a sixpack.You aren't sure whether he works out,but he has attributes for one.

Or a guy who doesn't seem like the type to work out and doesn't show off the fact he has a sixpack.Only few people know that he has one.

Girl 1:I wonder what Joe does after school.
Girl 2:Maybe he goes to the gym.
Girl 1:Hmmm,do you think he has a secret sixpack?
Girl 2:He looks like the type of guy who would.