When one walks facefirst into a large spiderweb that wraps itself around the head and neck. Bonus points if the resident spider ends up in mouth, nose, or eyes. Spazzing out is optional.
Bill: "Ack! Pfleth! Pthaa! Pfft! $&*#ing @%$#!"
Harry: (To Alice) "I think Bill just got a spiderweb facial."