I've eaten "squash" leaves several times as a stir fry in the past, in fact it's one of my favorite greens to eat. Very tender, tasty, and the "prickly" stuff actually provides an interesting sensation and makes it more substantial.

Probably was a summer squash or bitter melon leaf or vine tip. It just seems like a waste for all those leaves to go away at the end of the season, they're so big and beautiful!