Female version of a Nincumpoop. Someone who is being silly, stupid or without reasonable thoughts.
Sarah you big ninnie, you just put your car keys in the ice box

Or

If Beth is a class clown you might say
Beth is a ninnie
by ddlD2 March 18, 2014
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Most women are unhappy if they have ninnies
by Fisher March 24, 2004
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the fat round protuberances found on a cat's stomach; swell after giving birth typically to feed kittens; Also known as 'nipples'.
Kitty cat, put your ninnies away!!(said in a high pitched british accent); Don't show your ninnies in the presence of others (insert cat name), it's rude!
by Lester Hermit Mayfly June 10, 2010
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THE SHIP NAME FOR VINNIE AND NAILEA BC THEY ARE PERFECT FOR EACHOTHER
by January 18, 2021
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