Once had a compiler QA gig. Was kinda lazy. So, I wrote a nonsense code synthesizer. Just take the BNF and belch out code. Millions and millions of lines of code. A fun variant was to create a class hierarchy that would run 100's of levels deep. I showed it to marketing. They asked: "Can you do that for <competitors> compiler?" "Sure thang!". Soon, there was an ad showing how our compiler could handle a lot more bloat than their compiler. Not my proudest achievement.