all right so far, OK, why not?, I can let it pass, that I can tolerate, ... is one thing (but...) (used to say that the first option is (barely) tolerable, but that the second is too much)
I beg you, please; go ahead, please, help yourself (response to being asked permission, e.g. to come in, to pass someone, to start eating); you're welcome, don't mention it (familiar, in response to a thank you)