nipple mouse n.
Var. `clit mouse, clitoris' Common term for the pointing
device used on IBM ThinkPads and a few other laptop computers.
The device, which sits between the `g' and `h' keys on the
keyboard, indeed resembles a rubber nipple intended to be tweaked
by a forefinger. Many hackers consider these superior to the
glide pads found on most laptops, which are harder to control
precisely.