1. Term used to describe an individual who is so totally oblivious to the world surrounding him/her that he/she can totally fuck up whatever you were attempting to do at the same moment. Even though you were right there. In plain sight. Staring right at them. The whole time. See Example "A".
2. Term used to describe someone who has WAY too much fun doing the most fruitless of tasks. See Example "B".
3. That odd fellow who has been living in a van down by the river, living off government cheese, who thinks that life "Shoo don git nah bettah than dis! (cackle, cough, hack, and spit)" Also has a "Homemade Bait" stand on his front passenger seat. See Example "C".
Example A: As Ajax was attempting to pull up to the pump for gas, that Happy Asshole pulled in right in front of him, got out, gave Ajax a friendly wave, and began filling his own car up.
Ajax: "Clarence sure loves mowing his lawn, he has been at it for hours!"
Joe: "Yeah, but his mower doesn't have any blades in it!"
Ajax: "What a Happy Asshole!" (Smiles and waves to Clarence, who is grinning like a man with tits in his hat)
Example C: C'mon, we all know that guy. He has that wonderful aroma of old cheese and cat urine wafting around him.