Being a teenager is bad enough when you don't have a sibling who thinks everyone should bow down to them. And on that note, this story is about sibling rivalry at its finest. One 15-year-old uploaded screenshots of a baffling conversation he had with his condescending sister who left him stranded for 3 hours at school after an exam he had. Apparently, their kindhearted mother had given his sister some money to use to get an Uber for him once he'd finished his exam. The money was meant for that,…