If you find it difficult to awaken kids on school days you can take revenge with this nasty little alarm. Simply pull the pin out, throw it through the bedroom door and cover your ears. In 20 seconds the sonic alarm will let out an ear blistering racket which will be sure to wake the heaviest of sleepers.

To add to the amusement once the intended victim has been woken up and retrieved the grenade from under the bed they can’t simply turn the alarm off. They now have to either put the alarm in a sound proof box or replace the pin (a good place for which would be on the breakfast table).

Be warned, this alarm could quite easily be lost being thrown out the window which could get a bit expensive if some sulky teenager doesn’t open it first.

You can get the Sonic Alarm from i want one of those for under a tenner, though you may need to get more than one.