I'm usually a folding station and would probably be pretty happy to get all-in here. It does look a lot like a 66 but KK is very unlikely and he can only have 1 combo of 88. There's both straight and flush draws out there for hands that might limp on the button and given your image he could be "stringing you along" with a much weaker hand. Also the mini-raise could be a draw trying to take control of the hand and possibly get a free card. It does suck to lose 100+ bb's in an unraised pot but I don't think you lose much here in the long run. If you do manage to fold top 2 against a set that's money you made because you'll probably get paid off anytime the situation's reversed