you can just sit there, pissing and shitting yourself
An expression, commonly used in a negative way in order to tell someone to go fuck off. It can also be used in a "you know what?" kind of manor, as an exclamation or frustration. It has the added benefit of insulting how the recipient spends his free time, and is synonymous with "you just sit on your ass all day"
Bill: "Hey, you wanna hang out today?"

Jon: "Nah I'd rather just stay home and watch a movie."

Bill: "Fine then, you can just sit there, pissing and shitting yourself all day."

Fred: "Hey, we're gonna play some basketball, wanna come?"

Joe: "I just had a really bad break up, I'd rather be alone."

Fred: "Well you can just sit at home, pissing and shitting yourself while we have fun ya douche."