The expectation: "This won't take long, I can just reuse code from another project."
The reality: A Frankenstein's monster of incompatible parts desperately duct-taped together, much like Bugs Bunny's makeshift outboard motor that somehow still floats but is one runtime error away from catastrophic failure.
Copy-pasting code is the software equivalent of trying to fit square pegs in round holes while blindfolded and underwater. Sure, it compiles... technically. But what you've created isn't elegant software—it's a digital crime scene waiting for a forensic code reviewer to discover.