A mechanism that aborts the current ball in play if the player shakes or nudges the game too hard.

It's a penalty for shaking the machine too much. Basically what happens is the machine says "TILT" on the screen, the flippers stop working and all targets stop responding until the current ball goes down the drain. On some machines, all of the lights will go out as well. When the ball goes down, the next ball is started as normal. Extra balls that have been earned will remain, but a tilt will forfeit any kind of "ball save" mode (On some machines, under normal play, if the ball goes down before, say, 15 seconds have passed, it will kick it back out without changing the ball count, sometimes accompanied by "ball saved" flashing on the display) In case you're wondering how the machine senses shaking, it's basically a cone-shaped metal doodad hanging by a wire in the middle of a metal ring, both of which are electrified. The game responds when the hanging cone touches the metal ring. Some machines will, instead of immediately tilting when the sensor activated, give 1 or 2 "tilt warnings". basically the display will say "warning" "careful" or "danger" and if the machine was shaken hard enough that the bobbing cone bounces back and triggers again, or if shaken again after this warning, it will then tilt. Most machines are set up such that some gentle bumping is allowed to add a little more ball control. Adjusting the sensitivity is as simple as raising or lowering the sensor bobber thing. The sensor is there not only to prevent cheating but also to discourage abuse because getting too aggressive could damage the machine.

when you fall over from to many beers "IM ON TILT"