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3. jackball
knucklehead, fool, dummy, idiot, moron; depending upon the context.

Jackball is word for which the meaning is subjective and entirely related to the user's state of mind. It ranges from the 'knucklehead' to the 'idiot' or 'moron' end of the scale depending upon whom you are referring.
Example: When addressing a friend it is more likely meant in the 'knucklehead' sense. If you were driving down the road and some manic cuts you off or you're watching TV and Bush is trying to complete a sentence or pronounce the name a of a foreign dignitary and you yell, "JACKBALL!" Clearly, it is being employed in the 'idiot' or 'moron' sense.
1. jackball
a dum person who just keeps getting dumber
my boyfriend
by linda rondstat Aug 10, 2003 add a video
2. jackball
A dumb person who just keeps getting dumber.

As heard on the Rush Limbaugh show, which gave a shout-out to Urban Dictionary regarding this word.
Ardent John Kerry supporters are a bunch of jackballs!
by Hyacinth Bucket Dec 30, 2004 add a video
4. jackball
Can be used as a verb, meaning the deliberate act of taking or stealing. A jackball is a small "victory" for the jackballER and an annoyance to the jackballEE. It can often be advantageous for the jackballER to appear unaware of the jackball if noticed or confronted.
That lady jackballed my spot in line!

If this guy gets up, jackball his seat.
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