I wouldnt think so. When kids stumble upon something that 'works', they do it again. Be it throwing themselves on the floor, stomping their feet, or holding their breath! We've just gotta try our hardest not to let it work for them. Yours just happened to find something that scared the crap out of you guys and got an almighty reaction, which imo is totally reasonable!

LOL Christy at the water pistol. Great idea! Think Id prefer screaming too.