I know if someone had pulled that cell phone signal conversation parroting trick on me, I'd have gone into a murderous rage. Everybody's different.
The "we're out of cereal" trick seems interesting though. But at what point are you not letting kids learn how to be confrontational? It's annoying, but it's an important life skill.
Really? I'd say it's the opposite. Being confrontational is easy and the important skill is training yourself not to interact aggressively with other people - in my experience at least, the success rate for getting what you want is much higher if you don't turn an encounter into a fight.
The "we're out of cereal" trick seems interesting though. But at what point are you not letting kids learn how to be confrontational? It's annoying, but it's an important life skill.