Ever catch a signal you couldn't immediately explain?

One of my favorite things about radio is that occasionally something comes
through that makes you stop what you're doing.

A strange digital burst.

Half a conversation.

Some distant station that shouldn't be reaching you.

A carrier sitting there doing seemingly nothing.

Probably perfectly explainable.

Probably.

This thread is for those.

Post weird signals, mystery transmissions, unidentified digital modes or
anything else that made you stare at the radio for a minute.

Bonus points if you recorded it.