Breasts (normally female) that are either so ugly, or so freakin hot, that people who see them (either clothed or not) turn to stone out of sheer shock. Those who do usually don't recover unless they watch some boring political discussion, which usually drops them out of the shocked state.
Jim: "I see that Jenny has some medusa boobs."
James: "How do you know?"
Jim: Didn't you hear? She took her top off for the guys at her party. Nobody could move afterward, they were so hot."
James: "Sweet. Let's play video games."