I had a little Welsh friend at school called Susan Jones (honestly!) and she taught me how to pronounce the incredibly long name that starts Llanfairpwll etc. She was most insistent that I 'did' the lateral lingual fricative correctly.
My husband wouldn't believe for one minute that such a long place-name existed until I showed him a photograph online of the yards-long sign!
I also had a little Jewish friend who taught me the Hebrew prayer that begins 'Baruch atah adonai'.
And a little Chinese friend called 'There is a Fairy In the Moon' (in Cantonese) who taught me to count up to ten in her native language.
All this when I was at Infants School!
I used to rabbit on in all these languages - my poor mother used to wonder why I never ever shut up. I expect people still wonder nowadays teehee.