When the hair on, in and/or around your asshole becomes a tangled mess, not unlike that of a spiderweb. This mass of hair has a tenancy to catch small pieces of debris going in or out of ones asshole. In extreme cases, pieces of fecal matter, aptly named dingleberries, up to 3oz. in size. These "dingleberries" have a profound habit of tugging on the web of hairs, creating a very uncomfortable sensation known as "web-swinging". Also in other extreme cases, shitting causes the pulling of hair as the shit comes out with a feeling of a pulling sensation on your ass hair. The only known combatant of Spiderman is the Green Goblin or a friend with scissors.
Alleh told Richeh to trim his ass hair because Spiderman was relentless in giving up.