Accidentally alt-tabbing to an equally inappropriate window when your boss/parent suddenly appears.
Man, I had like...15 windows open on my PC at work today and only one of them was the report I was meant to be working on. Clicked from Facebook straight to YouTube when my boss appeared. Just a big-arse kitten playing a piano on my screen. Complete e-fenestration.
The burning need (whilst stoned) to both lie down, get up and eat something, drinking something and play more Mario. This creates the ultimate paradox in that you can never be doing what you want to, despite attempting to do what you need constantly.