A person who consistently acts like a dumbass but thinks of himself as a smartass. A certified Jackass may never be thankful, no matter how nice someone has been to him.

In other words, a Certified Jackass is someone who shows traits of a Jackass on a regular basis.
Person: I left you an a treat on your desk
Certified Jackass: Does that mean you are ass kissing me now?
Person: Great! So instead of thanking, you are going to be a Certified Jackass that you are!
by Smurf with Blue Eye Liner March 7, 2012
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