A bit like an orgasm, but not quite. Originally used to describe a cheap but delicious icecream made by students (and named from the surname of one those students) with own-brand vanilla icecream and peanut butter, now it can be used towards any pleasurable experience that isn't quite an orgasm. Antonym, see: Beckers.
"I'm out of desserts but I could totally mix up a batch of kiggins." (Archaic)
"You know, I hear we can actually have snow days at uni."
"What, like no lectures? That would be so kiggins."