Want a very quick diversion? Try Double Jeu. It's in French. The two words you need are: jouer (means play) and rejouer (means play again). This is a very, very simple game. Your aim is to keep playing as long as possible. It may drive you round the bend.
Halfway up the screen is a Pong-style bat which moves horizontally. Use it to keep a small bouncing ball within the top of the screen. This is controlled by the mouse.
You also have a horizontal bar, which pivots around its centre, three-quarters of the way down the screen. A ball on it rolls left or right depending on which way the bar is tilted. Your aim here is to keep the ball on its bar. This is controlled by the mouse.
Yes. Two things, one controller. Try it.
I found my first few tries to be fraught with failure, as I learned how to control two things at once. My first decent go (I proudly announced it in an IRC session as lasting 32.823s) ended with the ball on the pivot staying roughly in the middle, and the top ball bouncing madly almost vertically at the centre of the screen. When you first are in this situation, laugh along with me.
The one tip I can think of is to predict where the Pong bat will need to be, then keep it over the other side of the screen to that for as long as possible. This allows the pivot ball to have a chance to roll one way, then the other.
Analysis: Either half of Double Jeu would be incredibly easy to play indefinitely. Add them together and you have something which seems to be either positively reinforced (if both games want you to move the mouse right, for example) or negatively reinforced by their combination. The trick (and my tip tries to achieve this) is to try to keep the games positively reinforcing each other.
Go on. Have another go.
Cheers to Ebenclaw for suggesting the game!