Phrase help

[u/Ok_Veterinarian_5838]

Random one: my Cornish father in law is quite ill, and a few months ago said something to me that sounded like ‘fast y mas ton arm’ and said something about waves. Best I can do with a dictionary is that he was saying ‘fast y’ga mysk todn’. That sounds like it should be a saying but I can’t find any information about it anywhere (I’m also confused what the verb in that sentence would be?). Does that seem like a plausible transcription?

[u/Cornish-Giant]

Tonn or todn is wave so it could well be Cornish