I just remembered a good one:
A couple of my friends at work, Adam and Aaron, were both in the office fairly late of an evening. Adam walked into Aaron’s office and loudly proposed, “Hey, douchebag - are we going to the pub?” Aaron immediately scrambled for the mute button on his phone and shouted back, “I’m on a call, you fucking dickhead!”
Unfortunately, it turned out that Aaron had missed the mute button.
There were apparently about a dozen other people on the conference call.