This is something that I have started to see lately at restaurants and I do not understand it. Maybe it is because I do not like mayo and think the only place it has on a burger is as a moisture barrier on the bottom piece of the bun. (Of course this can be negated by toasting the bun slightly.) I do understand that other people like it. But why would it be added to a burger that already has a very flavorful condiment like BBQ sauce as an integral part? Does anyone have any ideas?