I have a good friend who works for an major US Airline in security and has for 37 yrs, Thursday he told me a new one I had not heard of, an incident they had, a passenger, male in his mid 20's, not US citizen on a flight here in mid flight started taking his shoes and socks off and eating his socks, chewing holes in them. Then went to his shirt chewing holes in it, all in mid flight, the Air Marshal was called and they moved him to the rear and subdued him for the rest of the flight until they landed and turned him over to authorities for mental evaluation, the man and lady next to him thought he was going to eat his pants next and were concerned quote: he might get naked! They said. My friend said he had never seen anything like that.
@Tex Dennis As a kid, my Mother told me of an eating disorder called "Pica". How this foreign-born lady accumulated the wealth of vocabulary and understanding of English I never knew. Anyway, "Pica is a psychological disorder characterized by an appetite for substances that are largely non-nutritive, such as ice (pagophagia); hair (trichophagia); paper (xylophagia);[1] drywall or paint; metal (metallophagia); stones (lithophagia) or soil (geophagia); glass (hyalophagia); feces (coprophagia); and chalk." See: https://en.wikipedia.org/wiki/Pica_(disorder) Stomach contents of a psychiatric patient with pica