Here's a story with a (sort of) bad moral that I came up with:

One day a guy named Bob was running for school president against a guy named Joe. There was a person named Bill who liked both Bob and Joe so Bill told both Bob and Joe that he would vote for them. Bill obviously told Bob when Joe wasn't there, and he told Joe when Bob wasn't there. So both Bob and Joe were convinced that they would get voted on by Bill. Oh and by the way Bill is a bad person but we'll get to that later.

Okay so one day Bob was sure that he was better than Joe so he came up to Joe and boasted about it, "Bill told me that he would vote for me, isn't that great?!"

Okay so usually anyone would take Bill's remark personally and keep it to themselves, but Bob being Bob decided to boast.

Anyway Joe was like, "What? Bill told me that too!" And everyone knew that Bob and Joe were good students who were honest so the teachers decided to investigate.

Meanwhile Bill was wreaking havoc to the school while no one was looking and he didn't get punished because no one knew who wreaked havoc.

So Bob and Joe told the teachers that Bill told them that he would vote for them. The teachers came up to Bill and punished him. That means Bill got punished anyway haha even though no one knew he was the one who wreaked havoc to the school.

So now you know why this story has a (sort of) bad moral. Don't take this story seriously as it was just something that popped up in my mind lol. Please don't use this as an example of what to write if you wanna make your story have a good moral.