Top Definition
The modification of a car or truck purely for performance gains, while leaving the outward appearance unchanged.
Are you going to keep the chrome tip on your performance exhaust system?

no I'm going for the sleeper effect.
by Dastoymaker November 09, 2007

The Urban Dictionary Mug

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The Urban Dictionary Mug

Lotsa space for your liquids.

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The Urban Dictionary Mug

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The Urban Dictionary Mug

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

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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).

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