I was fixing a little ship, my own one-man command, little more than a souped-up runabout on a slightly larger scale really. There was this flat space in the mountains, and I was sitting underneath my ship, happily singing "Calon Lan" while trying to reconnect some gubbins in the impulse drive, when I was interrupted.
There was a Starfleet crew. They'd arrived to survey the planet, and spotted my life sign and the ship, so they'd come down to investigate, and see if they could help. And of course, the leader thought I was some sort of an alien because she'd never heard any language quite like the one I was singing with, and the universal translator was having a hard time trying to parse what it was I'd been singing.
I told her that I wasn't surprised - it was Welsh:-
Depicted: The Delta Flyer from Star Trek: Voyager