To rapidly slow down or stop a moving vehicle by mashing down the brake pedal. So named because of the tires skidding when done in a car without anti-lock brakes.
Can also be used in a metaphorical sense, in which it means to halt whatever action or process is currently occurring.
The police were waiting with a speed trap around the bend, so I hit the skids.
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.