1 definition by Ballerado

Top Definition
Another way of saying retarded, or down syndrome.

When you have down syndrome, you have an extra 21st Chromosome. So by saying someone has an extra 21, you are essentially saying they are retarded, or have down syndrome.
You and Abby didn't do it last night? She was totally into you. Someone must have an extra 21.
by Ballerado December 01, 2010

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