"Golden Brown" by The Stranglers during the scene when Mickey knocks out Gorgeous George and "Fuckin' in the Bushes" by Oasis for Mickey's last fight are particularly excellent examples.
"Disco Science" by Mirwais during the hare coursing scene definitely qualifies for this.
Massive Attack's "Angel" is perfect for making the burning camper scene all the more intense.
Complete Monster: "Brick Top" Pulford is a ruthless underground fight promoter with a penchant for Disproportionate Retribution. Brick Top is introduced having a traitor, as well as the one who reported the traitor to him, tasered, suffocated with plastic bags, dismembered, and Fed to Pigs. When a gang of Yardies rob his bookkeepers, he attempts to murder them, only releasing them when they promise to give him a diamond they have stolen, giving them 48 hours to give him said diamond. When Turkish informs Brick Top about the demands their fighter, a Traveller named Mickey, is making, Brick Top has Turkish's slot machines vandalized, and has Mickey's mother burned to death in her caravan. Subsequently, Brick Top threatens to massacre Mickey's entire clan if he doesn't throw the fight.
Crosses the Line Twice: Often, the plot is so ridiculous that the violence circles all the way back to being funny. One example is the car accident scene, which has to be seen to be believed.
Genius Bonus: Avi sneeringly refers to Boris as a "Cossack." Cossacks were responsible for anti-Jewish pogroms in Russia, so this is a great insult for the Jewish Avi.
Ho Yay: Turkish and Tommy are Heterosexual Life-Partners, so they get these jokes in-Universe (such as Tommy repeatedly referred to as Turkish's "girlfriend" or "lady friend".
Jerkass Woobie: Cousin Avi isn't a nice man by any means — in any other movie he'd probably be the villain — but he's subjected to so many indignities over a diamond that is (sort of) supposed to be his anyway that by the end you almost start feeling sorry for him. It also helps that he appears to be a relatively Benevolent Boss to his employees and, compared to some (hello Brick Top) is far from being a Complete Monster. (Appropriately, he does get (implicitly) his diamond in the end.)
Memetic Mutation: "You can call me Susan if you like" and Brick Top's "Greedy as a pig" speech often show up on the Internet.
Moral Event Horizon: In response to learning that Mickey wants a caravan for his mother in exchange for fighting, Bricktop responds by having Mickey's mum's caravan burnt down. While she's still in it.
Nightmare Fuel: Brick Top in general. Particular mention goes to his calm, matter-of-fact lecture on the best method to dispose of a body. Doubles as Nausea Fuel.
Brick Top: You're always gonna have problems lifting a body in one piece. Apparently the best thing to do is cut up a corpse into six pieces and pile it all together... Then I hear the best thing to do is feed them to pigs. You got to starve the pigs for a few days, then the sight of a chopped-up body will look like curry to a pisshead. You gotta shave the heads of your victims, and pull the teeth out for the sake of the piggies' digestion... You need at least sixteen pigs to finish the job in one sitting, so be wary of any man who keeps a pig farm. They will go through a body that weighs 200 pounds in about eight minutes. That means that a single pig can consume two pounds of uncooked flesh every minute. Hence the expression, "as greedy as a pig".
One-Scene Wonder: The agent at Brick Top's bookie's (played by an uncredited Sidney Sedin), whose attitude during the entire robbery scene can best be described as "bored resignation" whether explaining why there isn't any money or thwarting the robbery single-handedly.