The Annoy-a-Tron by ThinkGeek “generates a short (but very annoying, hence the name) beep every few minutes.” Video after the jump.

Your unsuspecting target will have a hard time ‘timing’ the location of the sound because the beeps will vary in intervals ranging from 2 to 8 minutes. The 2kHz sound is generically annoying enough, but if you really really want to aggravate somebody, select the 12 kHz sound. Trust us. The higher frequency and slight ‘electronic noise’ built into that soundbyte will make a full-grown Admin wonder where his packets are