My best man was married a few years before me and had a son just old enoght to talk. On this particular day I was around his house and the conversation got around to buying things. He had bought a two way intercom with one end in his sons bedroom and the other in the lounge.
Next I was treated to a demo of this bit of equipment after his son went to bed.
It went like this to his son Ian
he said into it “Ian”
no answer
“IAN” in a louder voice
finally in a very loud voice
“IAN”
then a small voice answered
“what do you want wall”
I curled up laughing