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Someone who initially appears intelligent but is found to act idiotic in the majority of situations.

A Niddy will - act without thinking
Ask the same question more than twice
Not be able to see something directly in front of them
Have a terrible memory
Be extremely clumsy
Overuse telephones
Think that sarcasm is wit

Under no circumstances can a Niddy multitask nor even think and speak at the same time.

Can also be used as an alternative monika for males named 'Christian'.
"OMG, he's such a Niddy! Even though it's cleary written on the packet and I explained it to him 6 times, he's still eaten the bar of laxative chocolate! Niddy!"
by bighobo February 04, 2010
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