I'm not sure if it still does, but twitter used to hijack F5 so you can't reload...

keeperofdakeys on March 22, 2014 | parent | context | favorite | on: Why Does Backspace Go Back A Page?

I'm not sure if it still does, but twitter used to hijack F5 so you can't reload the page. Rather annoying when it has been sitting in the background, and hasn't updated.