Because otherwise they would be unable to track movement and move the cursor in the computer screen.
Which hole they stick their finger in when no-one's looking.
In case he got a hole in one! Ha Ha Ha Ha
I don't know, I lose track of time when I have an erection.
All seven or eight of them.
Bubble and squeak !
Mick e-mouse.
His vision was based on movements.
Because your foot would go right through the computer screen!