This is the cousin of the dingleberry , this happens after masturbation. It is when a globule of your jizz gets onto your cock bush and you forget about it. Later, it dries up into a ball and can go unnoticed for a while, unless you take a shower.
Zakk: Dude, at camp, I rubbed off some knuckle children and got a nasty farkleberry.
Henry: ohh god, don't you guys only have showers, like, once a week?
Zakk: Yeah it was disgusting.
When one finds bits of fecal matter debree wedged inside of the anal crevis.
When you use the bathroom and wipe and you feel something pulling on your anul hair you get in for a close examination and realize you have a farkleberry.