"Always Expect The Unexpected" - End Users

The four horsemen of software development reality! What starts as a sleek feature with fancy wheels quickly turns into a normal stroller during dev testing. By QA testing, someone's frantically running with it like they're late for a meeting. Then the ACTUAL USERS? They're doing skateboard tricks with a baby stroller while the baby flies out! No wonder developers wake up in cold sweats. Your perfectly engineered baby carrier somehow becomes an extreme sport equipment in production. This is why we can't have nice things in software—users will find ways to break your code that would never occur to a sane developer's mind.