How are u supposed to respond when ur compared to a celebrity?

allright im not trying to be a d*k or wtv, i just thought of a bunch of things i've always wondered, but when girls u know/kind of know, say something along the lines of u look like john mayer(i dont think hes good looking but wtv) or u look like the che guevara guy or freddy rinze jr, i know its a compliment, but what do i do complement the girl back, cuz i hate being corny and dont know how to deal withthis