A sense of impending doom or extreme apprehension. Refers to armpit perspiration that accompanies a frightening or uneasy situation. Used as an excalamation or a noun.
"Pitters dude! I'm running on empty and it's a hundred miles to the next gas station."
"I've got some irreversible pitters going about this project for work. My boss has been riding my ass all week and I haven't even started yet.