la raja
It's the evolution of me cago en tus muertos, and it means 'I shit over your dead parent's ass cracks.' It's like your grandpa's butt is getting a second opinion from a toilet.
I told my teacher, 'Me cago en tu raja,' and got sent to the principal's office.
I said 'me cago en tu raja' to my brother, and he cried like a baby.
My dad said 'me cago en tu raja' when my mom forgot his birthday.