If something goes 'down the pan' or 'down the toilet' it means it is wasted or ruined.
Mike had great dreams of becoming a rock guitarist, but they went down the pan when he injured his hand.
I'm afraid all that careful preparation we did for Meerka's surprise birthday party went down the pan when her sister told her about it.
He invested all his life's savings in a beautiful, antique car but everything went down the pan when he crashed it the next day.
Don't confuse it with
If something goes 'out of the frying pan, into the fire', it means it goes from a bad situation into an even worse one.
Studying for my MA was really difficult and stressful, but then I really went out of the frying pan into the fire when I graduated and realised there were no good jobs available.
In British English, the word 'toilet' can refer to the fixture itself or the room where it is installed, for which you will also hear the more colloquial words 'loo', 'lav' or 'john'. The slang word 'dunny' is popular in Australia while Americans tend to prefer the more polite terms 'bathroom' or 'restroom'. In the Philippines, the term of choice is the pleasant-sounding 'comfort room', or 'CR' for short.