Pull A Maddy

To announce that you're about to say something, then refuse to say it.

Person A: I just thought of something really funny- wait, I shouldn't say that
Person B: Come on, don't Pull A Maddy

leo moment

Attempting to do a task before getting completely distracted by something unrelated

Person A: Did you do your homework?
Person B: Argh, I meant to, but then I got distracted by researching penguin anatomy
Person A: That’s a Leo moment