I hit Marian with a frying pan - a saucepan wasn't any good. Or My hen caught a haddock and had it for tea but she didn't like it and gave it to me... I'll have to ask my dad for those ones.

I can't speak Welsh but proably the most common one for mixing up languages is the counting goats song It gets good when it gets to navy-blue by which time the Welsh words for colours seem to have been forgotten.

Jon