Yup. If I'm going around my daily business wearing a shirt that says, "no sex for me, please!" Then please do not come up to me and say, "but, would you like to have sex with me?"

And if I say "yes, actually, even though it was very rude of you to ask, given the shirt that I am wearing...in fact, I would like to have sex with you," then you should at least have the decency to wait for me to take my shirt off before having sex with me.

If I decide it's really not worth the effort to take the shirt off, then it turns out, actually, no, I really did not want the sex after all.