Oh, man...

. Yeah..."if it works, it works", also known as "working as coded".
The typical sequence of events, goes something like this...
Stage 0: "I was on the phone to the head of department at 3 AM this morning, our biggest customer needs this bug fixed ASAP, and we need you to stop what you are doing right now and get on the job".
Stage 1: "we're not quite sure what it does, the guy who wrote it left 4 years ago, but it works, and whatever you do, don't change it while you fix the bug".
Stage 2: "no, we don't have a functional spec., and there's no unit test plan either".
Stage 3: "what do you mean 'Is there a regression test?' Not unless you're going to write one".
Stage 4: "will you have the fix ready by this evening? We need to know!"
Stage 5 (a few hours later): "ok, just check in what you've done so far, we're going to ship it!".