Does your dad speak german? it could have been gibberish with a german accent lol... but that is a funny thing hahah. I told my mum to donate money to save the wales in my sleep once...!
Wow, this has actually happened to me (apparently). 3 1/2 years ago I was camping with my friends in Essex and apparently started speaking German in my sleep. I don't know if I made any sense though because I'm not very good at German and my friends don't understand German at all.
I haven't done it in my sleep yet, but I did it perfectly when I nearly fainted on holiday. I think I passed off as native and I was quite proud. I'd love to speak German in my sleep
Seriously, that happened to me once but with Rumanian, I don´t know if I was making it up in my dream or what, but apparently I was speaking Rumanian and talking about the grammar.
Slightly off-topic, but I have a friend who is half-German. On a lengthy pub crawl around Hull a few years back he was found in a pub toilet, vomiting his guts out and babbling to himself in German, trying to work out how drunk he was...