Aruch HaShulchan 167:31 and Be'er Hataiv 167:22 both say that it is forbidden to throw the (Challah) bread. I have heard that there are some people (I heard that there are some Rabannim who do so) that have a Minhag to throw the bread when passing it around Friday night. Is there a source for this Minhag? What is the reason? How does it circumvent the problem of throwing bread?
i have been told that the actual custom is to not pass it by hand but rather to place on the table or a tray for the others to take, and not necessarily to throw it. the reason being that the challah is zecher for the "mon" that was given directly by Hashem and therefore it (the challah) should not be taken from a person directly.