Throwing bread at hamotzi
Years ago I found myself at a Shabbat table in Jerusalem where the challah was actually thrown to the guests around the table. I was shocked. Since when were adults allowed to throw food?
Rabbi Yosef Karo author of the Shulchan Aruch explicitly forbids hurling bread. However, he also says that one should not place it directly into another's hands, for that is how one treats mourners. Maimonides teaches that on the first day of mourning you should not eat your own food. To this day, one brings food to mourners. While today we might leave a home-made quiche on the kitchen table, in the past, it seems people actually placed the food into the mourners' hands.
In some communities, the ban on placing bread in another's hands morphed into throwing it, with the post-facto justification that no bread was ruined in the process. However, there does not appear to be any actual rabbinic endorsement of this custom.