Scared the crap out of my gf, made her piss herself omg Im FU*KED?

lol say it was a joke and you're very sorry, show little gestures to prove it like doing cute lil things for her. leave notes around saying sorry i love you. give her flowers. take her out, be romantic and say that "you're sorry and that you'll never scare her again and if anything she never has to be scared cos you'll protect her ^^