"I am on the toilet!"
Translation:A mosdóban vagyok!
I'm not sure this is actually a good translation.
"I am on the toilet" means "I am on the pot". That is, I am sitting on the ceramic object used to eliminate waste.
I think that "A mosdóban vagyok" means "I am in the room where the ceramic object used to eliminate waste is", which would be more fluidly translated as "I am in the bathroom" or "I am in the lavatory", or even possibly "I am in the toilet" (although the last one sounds odd to this American's ears).
Am I wrong?
You can see the word "toalett" in several places on signs and doors, but it is rather an older, more aristoratically sounded expression often used by affecting people.
So basically you would never hear "Meglátogatom a toalettet." in the spoken Hungarian language nowadays (however 100 years ago it was 100% fine), you can rather hear it in a comedy or a cabaret where the goal is to make fun of how certain people behave and how they use odd words.