An ingress of water around the transducer. It can mean one of 2 things, either that you are trying to sound intelligent and threatening or that shit is about to hit the fan and the world will very likely end. It is everyone's worst nightmare (but nobody really knows what it is).

The horrible moment when you realise that you have accidentally done something very slightly wrong which has very bad (usually embarassing) implications for you. This is typically the moment of realisation that you just sent a dirty text message to a close member of family, typically your mother, rather than the intended recipient.