Top Definition
A baseball pitch which follows an unpredictable path. Very difficult for batters to hit and pitchers to throw. Only a handful of pitchers in the major league actually utilize it.
Tim Wakefield Throws the knuckleball so good, it literally corkscrews.
by Lutzie October 07, 2009

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The sexual act where you spread your partners rectal flaps with the knuckles of your index and fore finger, then cum with the screwball on a count of two balls and one strike.
The bases were loaded so I slipped her a knuckleball. Garth, she definitely won't be walking home any time soon. Two balls, on strike, and I'm out - she was like WTF!
by Lovell from UT November 04, 2010

The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

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The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt