This cute little styrofoam cup is meeting its gruesome end with a brave face.
Seriously though, the way acetone eats through styrofoam cups is mind-boggling, both in how fast it works, and because the cup seems to just disappear as if it's slipping through some weird chemical portal. How's it doing that?
The short answer is that acetone is a really good solvent, especially of polystyrene -- and styrofoam is just polystrene and a lot of air. When it dissolves it seems to disappear because styrofoam contains so little actual material. That said, no amount of scientific knowledge will help me feel less bad for that poor, evaporating smiley face.