The big LOL moment for me was when I connected my iPhone to my MacBook and it started charging the laptop from the phone.

I've always wondered how you or it chooses which charges from which!

You might have clicked a notification on either device on accidently and set it the wrong direction.

When you first connect, the power capabilities are negotiated and usually the more powerful device takes on the "source" role while the other gets to be the "sink".

This can be dynamically controlled and switched back and forth so some devices have UI to select what to do.