Wikipedia
Jeff Boomhauer, most commonly referred to as Boomhauer, is a fictional character in the animated series King of the Hill. The character is voiced by series creator Mike Judge, and is known for his nearly incomprehensible speech.
Boomhauer is the high school friend and neighbor of the characters Hank Hill, Bill Dauterive, and Dale Gribble. His first name was only spoken in the TV series during the 13th season episode, " Uh-oh, Canada", when the Canadian woman with whom he'd switched houses for the summer said, "Hello, Jeff. Oh my, it's the fifteenth already?". His driver's license as shown in the series finale reads simply "Boomhauer, Jeff".
The location of Boomhauer's house is inconsistent during the series. In the series finale, his address is shown on his driver's license as 73 Rainey Street, which would place him on the same side of the alley as Hank, Dale, and Kahn. However, in "Uh-oh, Canada", the rear of Boomhauer's house is shown to be across the alley from Dale's house, diagonally across to the right from Hank's back yard, which would place the front door of his house (and its address) on another street.
Boomhauer's primary pursuits are fast cars and women. He currently drives a 1969 Dodge Coronet Super Bee; in high school, he drove a late 60's Ford Mustang nicknamed "Ms. Sally" in which he had a lot of sex with strange women (the name being a reference to the classic Wilson Pickett song Mustang Sally) until the car was accidentally driven into the Arlen quarry by Dale, Hank and Bill while playing a prank on him.
Boomhauer spends most of his spare time drinking Alamo Beer with Hank, Dale and Bill in the alley behind Hank's house. While he enjoys his friendship with Hank, he sometimes has limited patience with Dale (whom he sharply refers to as "Gribble") and considers Bill "boring" due to his inferiority complex. Boomhauer favors animal-print bikini briefs, which have been observed a few times in the show when he's appeared without his blue jeans; he tends to overuse cologne, bragging about his Calvin Klein CK1 attracting women "like catnip". Boomhauer is a strict non-smoker who carries a lighter, implicitly for emergencies or for lending.
In an episode where Hank, Bill, Dale, and Boomhauer are stuck in the water because they jumped off a boat, Boomhauer confesses that he dyes his hair (" Hank's on Board"). According to his Texas driver's license, which is seen on the series finale, Boomhauer is 6 ft tall, 185 lbs, and has hazel eyes. Boomhauer is missing his left pinky toe, due to an accident while he was in the Order of the Straight Arrow (" Straight as an Arrow").
Boomhauer is apparently highly astute and often gives advice to his friends. He is also a frequent voice of truth, owning up to the wrongdoings of the group despite not always acting appropriately himself. Although since his speech pattern is not understood by most people, his confessions are usually ignored. In the episode " A Firefighting We Will Go", after Hank blamed the deceased Chet Elderson for causing the fire station to burn down, Boomhauer pointed out that Dale Gribble was the one who plugged in the malfunctioning Alamo Beer sign. However, the fire chief does not seem to understand him and decides that the blame for the fire will be placed on electrical problems, in order to leave the integrity of Chet Elderson's name intact.
In another episode, he mentions that his mother wanted him to become an electrical engineer. Given the opportunity, Boomhauer will demonstrate that he is, in fact, quite cultured. In " Ceci N'Est Pas Une King of the Hill", Hank Hill makes remarks about art that deride its modern state, provoking Boomhauer to call him ignorant, going so far as to cite Dadaism and the famed Marcel Duchamp work Fountain. He is the only character who initially understood the meaning behind Kahn's story at Buckley's funeral.
Three of the main characters (Hank, Dale, and Boomhauer) graduated from high school together (Bill did not complete his senior year having enlisted in the United States Army). Boomhauer was the starting quarterback for the football team, while Hank was a running back and Bill was an offensive lineman and a fullback. Dale, not being as athletic as his friends, was the towel manager. Dale Gribble referred to basketball legend Wilt Chamberlain as Boomhauer's idol in the season 11 episode serPUNt. According to Hank, Boomhauer is allergic to macadamia nuts. Boomhauer is the most modern of the four friends, and as such was first to own a cell phone.