The Scene: Flatemate in the kitchen, me in the other room relaxing in front of the TV.
FM: Hey gilly, did you know this plastic cup has a hole in it?
Me: Yup. It serves it's purpose.
FM: OK.
(Sounds of the microwave being used.)
FM: Uh-oh.
Me: What?
FM: Nothing.
(Get up from lounge, go to investigate. FM dearest has used said plastic cup to microwave chocolate sauce. Which is now melted all over the bottom of the microwave.)