Yup, kind of over-reacting. You don't want to lose a friend over something that silly. When you think about it,
he's not throwing away a 1/2 a bottle of beer you gave him, he's tossing away 2 cents worth of dough, and I will take
a guess he does this all the time, -- not just with your pizza. I DO know however, why you are feeling that way, it is a bit
insulting, if the invited guest *knows* you made it, and he tossed a bit of it out, and in front of you. I guess he feels comfortable
with you, and with what he did, and doesn't think he's doing something to make you feel badly, and insulted.
If you were in a pizza joint eating a pizza with this person, you wouldn't think twice about it. What they choose
to do with their crusts is up to them.
My kids never eat the crust of their pizzas when I made it for dinner.... and that suits me fine, as I eat them all
I love dunking the crusts into creamy Caesar dressing... great stuff.