Just learned a new word from a sentence discussion on Duolingo: bechingalw "thingamajig, watchamacallit".
After I looked at it twice, I could see the Be' chi'n galw? "what (do) you call (it)?" in it.
And I was surprised to find out that even the venerable GPC (Dictionary of the Welsh Language) has an entry for it! I thought it was simply modern slang, but presumably it's been around for a while.
So if you're ever at a loss for a word....
GPC notes a variant betingalw which might come in handy when you're talking to a single friend.