I hate speed bumps. Even a normal speeds, they always make me spill whatever I am drinking...

I would like to propose the following solution; a custard-filled, speed-sensitive speed bump. This bump would allow safe passage to all law-abiding vehicles. However, when a fast moving vehicle hits the bump, the magical properties of custard spring into life.

Custard contains finely ground cornflour and is a 'dilatant' mixture, changing from liquid to solid when pressure is applied. Thus, a benign, rather flaccid bump encountered at low speeds becomes an unforgiving, hardened lump when hit at speed. For blatant speeding > 70MPH, the hump would burst showering the offending vehicle with incriminating custard.

Military installations, could take a different tack, filling their bumps with custard powder. This takes advantage of custard's, better known, explosive properties...