A few years ago RAAF instructor pattering a student pilot with transmit button stuck open. He eventually twigs what's happening and tells student they are returning to the field and to maintain radio silence.
There follows ongoing endless droning of the engine for quite some time on the frequency. Eventually students voice comes over, whispering, " Do you think they can still hear us, sir?"
Followed by "I SAID SHUT UP." Then more engine droning.