I´ve just thought up of an answer that would make it a joke and relate it to jam. The answer could be, "wi jammin´" as in with jam in them, he likes his doughnuts with jam in them..."wi jammin´" not "we are jamming" but "wi jammin´" as in with jam in them
I would concur as long as it wasn't strawberry jam which I am not keen on. Does anyone have a joke about seedless raspberry?