When an individual flatuates, he or she must say the word "safety" in a clear tone so as to be heard by those around him.
If the individual fails to say "safety", participants may say the word "doorknob".
At that time, participants may physically punish the individual who flatuated.
The individual must immediately seek a doorknob 1 and touch it. Once the individual touches said doorknob, the beating must cease.
Many variations exist when doorknobs are either not accessible, or too accessible. A common variation is to replace the doorknob with something that the participants consider undesirable to touch, or something that is impossible, or nearly so, to touch.
^ In strict canon, only a true doorknob is eligible for play. However, in many social circles, house rules have been developed to allow the use of latches, handles, and other devices depending on the general availability of true knobs.