Take a bunch of grape juice and a bunch of fizzy stuff (club soda, ginger ale, lemonlime, whatever).
Mix them in a punch bowl.
Take orange sherbet and lime sherbet.
Scoop out scoops and float them in the punch, let them melt a little so that a nasty film spreads all over the top of the punch but there are still "bubbles" in it in the form of sherbet scoops.
Looks horrible, tastes just fine.