Several years ago in BVI, there was an active MAYDAY going on, the USCG was communicating with a sinking vessel (good conditions, no big winds or waves, sinking boat next to JVD close to shore).

Two ladies on two boats were on VHF 16 talking about which restaurant to head ashore to in the evening. The exasperated CG radio officer stated "This is the USCG San Juan and this is the emergency frequency. SILENCE MAYDAY". The last 2 word are the official terminology for "we're using this channel for emergency communications and if you're not part of it, then SHUT UP and stop transmitting.

Immediately, one of the ladies piped up and stated. "We were here first!"

To that, the USCG replied "What is your name and the name of your vessel?". That worked, as no response was forthcoming.