Noun. From Scottish.
“The intense feeling experiences just after jumping into cold or freezing water”
A cursory search online shows that curglaff appears to be an obsolete word in Scottish. It is, nonetheless, a very real thing and one that I fear, personally.
Unless you’re Tomb Raider’s Lara Croft, who can apparently jump in any temperature of water in any manner of outfits and still have the lung capacity of a blue whale…