A made up word used in the computer rooms of London's square mile by IT staff (geeks) who wish to break the monotony of being stuck in a noisy bland environment.
Gruntmoggy should almost be sung rather than spoken and can be used with any combination of other made up sounds.
In the late 90's it was not uncommon to find photocopied drawings of a mans body in black tie with a cats head. It's believed that this was the embodiment of Gruntmoggy.

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