My dog used to pee herself everytime she got excited and saw someone she knew/liked so when we were all on a car journey and my stepdad came back from the shop we stopped off at, she was so happy to see him she pissed herself all over the backseat of my mum's new car (new by like, 4 months?). My mum was still outside when it happened and needless to say she wasn't happy when she got in the car and smelt pee