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 Souphanousinphone.

He currently drives a 1971 Dodge Coronet Super Bee; in high school, he drove a late-'60s Ford Mustang nicknamed "Ms. Sally", 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 (Dale did not know how to drive a manual car and confused the clutch for the brake pedal).

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".

In the episode "A Firefighting We Will Go", after Hank blames the deceased Chet Elderson for causing the fire station to burn down, Boomhauer points out that Dale was the one who plugged in the malfunctioning Alamo Beer sign.

In "Ceci N'Est Pas Une King of the Hill", Hank 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.

[4] In season 3 episode 7, "Nine Pretty Darn Angry Men", Boomhauer, when asked about his employment during a lawnmower focus group, claims he's "done a lot of different things", and mentions something about receiving a tax-free worker's compensation settlement.

His heavy Southern accent and stuttering delivery sometimes leads to misunderstandings about his mental capacity; it has been made clear that he is an intelligent and sensitive person who expresses that in an inimitable way, such as a memorable occasion where the group's anger at Bill leads to Hank finding out he has the word "Bill" tattooed on his head, and Boomhauer chuckles as he says "life will throw you dang ol' curveball man, like dang ol' Sandy Koufax" (a reference to the legendary Hall of Fame pitcher who was known for the unhittable pitch Boomhauer described).

In the fourth-season episode "Naked Ambition", he was admitted to a mental hospital in downtown Houston after he drifted in on the river in a tube and was found in his Speedo, sunburned, drunk, and dehydrated, while his speech pattern was misinterpreted by a police officer as incoherent babbling.

There is a recurring joke in which Hank occasionally cannot understand Boomhauer due to extenuating circumstances such as the complexity of the vocabulary being used (i.e., "legalese mumbo jumbo"), a bad telephone connection, or an echo.

In one Rashomon-style episode, "A Firefighting We Will Go", it is implied that Boomhauer's speech sounds perfectly ordinary for his region in his own memory – contrary to how everyone else hears him – this being cited as "evidence of bidialectism".

Early promotional spots for the series featured clips of Boomhauer speaking, intercut with text that presented the term "Boombonics" in the style of a dictionary entry, as a reference to "Ebonics" (AAVE).

When demonstrating his abilities as a pick-up artist to Bobby, he was shown to lurk in a discount shoe store and hit on every woman he sees, receiving close to two dozen rejections before getting a single yes, suggesting that his luck with women comes from his persistence and lack of shame rather than any real charm.