For Xanadu, how about some popcorn, like Jackie and Mary eat while they're sitting in the bleachers?
For Passing Strange, how about a stew?
I haven't seen it yet, but one of the scenes in Top Girls takes place in a restaurant -- maybe something one of them were eating?
For Macbeth, a beef and cheese sandwich, like Patrick Stewart made when he was tempting the characters to do away with Macduff and family?
For A Catered Affair, some cake or scrambled eggs?
For Boeing Boeing, some airplane bottles of booze?
BroadwayEd