I think little girls with creepy giggles would work. What about playing tag with the bodies? or saying "Marco!! Marco!! You never say polo.. it's not fair, it's not FAIR!!!"
Singing a lullabye or kids song, then snarling could work too!
I personally like the quiet mouthing words, or wringing hands(acting nervous - twitching, darting your eyes, make eye contact for a second, then look away) then explode with fury, then go right back to timid
I agree that screaming is like the "go to" noise, and 9 times out of 10 it does NOTHING but annoy.
Do Vegan Zombies eat heads of lettuce?