When ice has unknowingly clumped together in the bottom of a drink container and spontaneously comes free only when the glass is tipped all the way back, giving the drinker an unavoidable cold splash of beverage and ice to the face.
This most commonly happens on a first date or when first meeting someone you're attracted to. Not exactly the (ahem) icebreaker you were looking for.
Hi nice to meet you Emily, my name is Patrick. Oh, so thirsty from working out all afternoon. (Gulp, gulp... Splash!).
Oh Patrick, you just had an ice dam! Let me help you dry off your half shirt.