Ha ha, I think your pet peeve (am I right in calling it that?) has to be dependent on culture. Like in Asia, if someone offers you something, you are not supposed to take too much unless you're really close friends or relatives. Otherwise, you're supposed to be polite and take slightly less than just enough for yourself and leave the rest for the person who offered and the other people who might get the offer as well. :)

But offer me chocolate, and I'll take a lot! XDDD

WRITING IS MY PASSION~