The act of covertly approaching somebody from the rear, preferrably while they are bent over, and inserting one's extended middle finger into their exposed anus. Traditionally, the activity is performed quickly, before the target has a chance to clench.
A 2011 national "safe snaping" campaign has fought to bring awareness to the need for using
sterilized rubber gloves while performing the act. The campaign was centered on the popular
young adult's novel "Cletus the Unicorn and the
Unwashable Horn".