That moment when you come home in middle of the night, and before going to bed you decide to go to the toilet.
You enter the toilet, and next to the toilet bowl you got your cat's litter box. And not to wake up your GF with the flushing sound you decide to piss not in the bowl, but in the cat box.
In the morning you get waken up by your GF who is smacking your head with a pillow and calling you a pig, because the cat didn't use the litter box you polluted with your urine, and instead used your GF's wardrobe to take a leak.
I was laughing so hard while I washed the litter box. In the end, I guess I couldn't wash out the scent of my urine, and the cat never used the same litter box again. FML. Had to buy a new one.
Happy days.