“Psst! Hey, buddy! Over here! I got somethin’ you need!”
I think this might be a relevant Wishlist topic:
In addition to the sound, though, what you really need is the compressed air cannon. When my cat moved in but began misbehaving, I read about using water pistols 
as a deterrent, but I didn’t want to be splashing furniture and have to wipe that up. I also read that if a cat starts biting you during play, then what you’re supposed to do is blow in the cat’s face and immediately cease play. I put 2+2 together and started using compressed-gas electronics dusters—not directly in his face but definitely aimed toward him if he was several feet away and scratching on furniture, for instance. That’s so effective that sometimes he’d stop just at my making a tsst! sound with my mouth, or he’d freeze and then run the other way if he saw a duster can in my hand. I wouldn’t even have to press the trigger.
I have also hissed at my cat. The first time I hissed back at him after he hissed at me, his eyes got wide 
, and he looked at me like, “What the 
?!” 
He’s used to it now, but that first time was a real eye-opener for him, in a very real sense.
If you really want to put him into pre-flight mode, though, just make a ding-dong doorbell sound. That gets him into position where he’s trying to decide if it’s cool or if it’s time to scamper beneath a bed and hide out for the stranger danger to pass. Even doorbell sounds in TV commercials get his attention.
That might not work with your chicken bullies, though.
This reminds me so much of how my parents acquired a black cat. 