How does one stop thinking about pink polka-dot elephants?
My dad would say to us, “Don’t think about pink polka-dot elephants for one minute.” I’m sure many other adults have said similar things. It’s obviously impossible not to think of something that absurd once the thought’s been planted in your brain by the question itself.
So… how do I stop thinking about something?
More importantly, how do I stop thinking about something when the fact that I’m thinking about it is frustrating me?

Think about something else. Or learn how to meditate.
[...] I didn’t even look at my To Do list. Adding new items didn’t count. Better yet… I didn’t fret about all the things that I needed to do when I got home. I knew I didn’t need to think about them… so I didn’t. On the drive home, I realized that I hadn’t been fretting all weekend. Mind you, I thought about pink polka-dot elephants a bit too much, but even that is s-l-o-w-l-y getting better. [...]
so…. “pink polka-dot elephants”… As good a euphemism as any, I suppose. I second the motion to “think about something else”, after calling your neural addiction to PPDE.