crusties used to be a punkish thing, similar to grebos[1], at the arse end of the 80s. I remember reading a Guardian column about the Halt Bar in Glasgow at the time – an ancient, legendary, sticky floored drinking bar – where they described the snug as being “known by the locals as Crusty Alley”[2]. No it wasn’t Mr G, I lived round the corner, although I’m sure the locals got a chuckle and a free pint out of making that up

[1] fans of bands like Pop Will Eat Itself, somewhere between punk and goth but mostly just wore whatever hadn’t evolved its own sentience and moved out of the student flat
[2] Ok I see I’m going to have to explain more pop culture of the era, this was a pun on Kirstey Alley, who was still on Cheers[3] back then
[3] Um, think The Good Place meets Zombieland. Just how young _are_ you?