Shake wearing the Shake Signal
The Shake Signal is a helmet-like device that Master Shake wears in the episode "Bus of the Undead", which lures Mothmonsterman to the Aqua Teen House. Shake claims that it "turns on whenever there is danger" (although it was on when he was watching a tv show at night). It was eventually shut down by Carl later that night, prompting Mothmonsterman to threaten the Aqua Teens into reactivating it.
In the episode "Super Squatter", the Shake Signal is seen on the roof of the Aqua Teen House when Shake haphazardly connected wires from his house to Carl's House in order to have electricity (since their house's utilities had been disconnected due to non-payment). Additionally, a signal from the device can be seen being projected in the night sky.