(American tourist on German train); one sneezes and the G-word is said nearby. She thinks it's an American er, idiom:
and wonders how Germans comprehend so much 'Murican? ..courteous passenger explains.
Dónnerwetter!

There are the known-Unknowns ..thence all the other stuff we screw up.
Large sympathy for your Pater; imagine.. havng to rewire your brainz--to a language whose M.O. is practically Martian-based in its OS! Worse than 'Doze --> Unix, eh?