As long as you've worn clothes that fit well to your body the imagination can fill in gaps and make guys uncomfortable around you. Its because they are attracted but know two things:LOL. You're hilarious. But I don't think it is the same for me. I don't dress in a revealing way.
1) They could be tempted to touch you in a way you DID actually mind, and when you confronted them on it probably freak out
2) They could take the fact you didn't care as an attraction to them and potentially damage or even destroy their friendship without because of a bad assumption.