Besides the usual type of tilt
sensor which kills your ball in play
on modern pinball machine
s, they are also equipped with a second type
of tilt sensor which usually requires significantly more effort (read
to trigger. The primary intent is to prevent damage to
the machine by slamming, kicking, etc. the front panel, or other activities
which could damage the machine. A slam tilt causes a soft reset of the game,
ending all games in progress.
Occasionally, a game with a loose coin door can trigger slam tilts
unusually easily with ordinary shaking of the game. Players often solve
this problem by wedging a coin between the door and its frame.
Due to the width required to wedge the door, the coin which fits best is
usually a penny, and this is called "pennying" the door.
It's customary when a group of friends are playing a multi-player game,
and somebody slam-tilts, that that player buys replacement games for all
players whose games were prematurely ended.