Translation:Mom and dad sometimes play guitar.
Non-native here. "Mom and Dad sometimes play on the guitar." Does the on make me sound stupid?
What ph said about context is right. I'd usually only say "play on the guitar" or "play on the piano" when the object is close by, or they're currently playing on it. If it's just general conversation, I'd say "I play the guitar". :)
Native and a guitarist myself, I tend to say play on guitar/jam on the guitar - as mentioned it's dependant on the context
It wouldn't make you sound stupid. It might be a little unusual, I think it might depend on the context. But I don't think many people would even notice.
Why is "Mom and dad sometimes play on the guitar," incorrect? Doesn't на mean on?