If you want to play an incredibly mean prank on someone, then the Sonic Nausea Device is the product for you. The intense machine produces such a high frequency sound that direct listeners will become instantaneously nauseous.
A similar design is often used in the UK to prevent people from overcrowding certain busy areas of the city. The product is licensed in the UK as 'the mosquito.'
The kit can come disassembled with instructions for $25 US, or already assembled and ready to use for $50 US. The high frequency sounds produced by the Sonic Nausea Device are very difficult to place, so the location of the device is not easily discovered making it the ultimate prank.
Be sure to use this practical joke device with caution, as there is always the risk that others will not appreciate your sense of humor.