I was working on some XML stuff and put superhero names in the test XML file. A week or so, some QA guy asked for sample XML and I gave it to him. Before I knew it, my test file was circulated in QA and Business Analysts for testing.

I guess they didn't read what's inside or didn't bother.

Then our client came and the BAs gave demo to them, using my XML file (I didn't know if they're going to use that!). The client were very upset with it.