I am not too convinced with the need for a waterproof mouse... but someone somewhere did and they went ahead and created it anyway.
The waterproof mouse wont break if you spill water on it as it's fully waterproof. It costs $17 and is available from USB Geek.
Waterproof Mouse Features
* 5-Button USB Silicone Optical Scroll Mouse
* Mildew and water resistant
* 100% waterproof, washable and hygienic
* Made by high-quality silicone
* Soft-touch, soundless while using
* 800 dpi optical tracking
* Optical sensor stays precise on the most surface without mouse pad
* Compatible with Windows Vista/XP/2000/ME/98SE
* USB interface (USB to PS/2 adapter included)
* Dimension: 130 x 80 x 48mm
* Weight: 172g
Product Page Via: Coated