the self-sufficient buttocks

I can't stop wondering why people always tell you to "get your ass" somewhere. Is the rest of you not presentable enough to go along? Your mother might say "get your ass to the doctor" which is fine if you're going to a gastroenterologist, otherwise shouldn't my dentist also check my teeth? What I'm getting at is the fact that an ass cannot just be traveling on its own. It needs a chaperone. I've never once seen an ass get up and walk out and leave the rest of someone "sitting". Imagine waking up one morning to find your ass missing and a post-it "gone shopping honey, make yourself some coffee". I can see the usefulness of having such a responsible and well-trained butt to be able to run errands and do shit (pun intended) you don't wanna do. Even sending it to the bathroom by itself can be liberating. Unfortunately we have not reached that level of sophistication yet at this stage of evolution so we're just gonna have to wait before that happens (and when it does there will also be a Malcolm in the forefront among them pushing for ass liberation from all the slave labor they'll be doing). Now an ass is like an underage kid and must present some form of ID in the shape of your face.