OK, if Azumanga Daioh was about the hilarious adventures of a group of girl high schoolers, Cromartie High School is about a group of male students who are juvenile delinquents. Cromartie has a reputation for tough guys, as proven immediately when Takashi Kamiyama, the most normal-looking student, drops a pencil. One of Cromartie's thugs picks it up, then eats the pencil! Kamiyama tests the lug by dropping a whole bunch of pencils, which the guy then gathers up and munches down on!
Other funny things include the revolutionary way of fitting in with a bunch of delinquents, a handbook read by Kamiyama so he doesn't stick out. However, things work out, because as Shinjirou Hayashida says, "say there was a rabbit, and it was living with a bunch of lions, and getting along just fine. That'd have to be one bad*ss rabbit." To which another student says, "I get it! Da*n, that rabbit rocks!" And even if you get into and win a lot of fights, it doesn't count unless you have a nickname, like "The Fireball of 2nd [class]" or "The Hospitalizer of 3rd [class]." Maeda is a good fighter, but as he didn't have a nickname, he's looked down on by his peers. However, he does have a mean-looking mom that scares his classmates.
Cromartie's surreal and bizarre appeal is based on three other characters introduced in the first volume. The first is a tall bemuscled guy with a thick bushy mustache, slicked back dark hair, who suspiciously looks like the guy who sings "We Will Rock You." He never speaks and nobody knows his name, so Kamiyama names him Freddie. I wonder why-ha ha. Then there's a gorilla, an actual gorilla, who proves to be more intelligent than many of the actual students, and who is seen wearing a wristwatch and making a call on a cellphone!
Finally, there is Mechazawa, a robot, basically a drum can with two headlight eyes dressed in school uniform, who's the brains of his homeroom class, constantly lifts the top panel of his head and oils himself with an oilcan, a satire of the 50's with the greasers. Kamiyama and his crony, Hayashida, who sports a Mohawk, aren't sure he's a robot and there's a running gag wondering if some of the other students will come out and say he's a robot. Or are their eyes playing tricks on them, is Mechazawa actually a normal high school student?
Other weirdness involves Takeshi Hokuto, the son of a rich financier who wants to control Cromartie High School, but is freaked out at seeing Freddie and the gorilla. As he mistakenly enrolls in Cromartie, which is a municipal as opposed to an elite school, he quickly makes up lies to get him out of this mess, such as that he's fighting his own father, the shadow prime minister and evil archfiend. The delinquents at Cromartie, however, have the intelligence of a pretzel and believe him, which deepens Hokuto's dilemma!
And Yutaka Takenouchi, the tough, bald, burly kingpin of Class 1, loves field trips and going to historic temples and such, but he gets motion sickness from vehicles and is prone to puking or fainting. So when Kamiyama accidentally sits down on him during the field trip, Takenouchi dares not lay a hand on him lest he barfs and lets everyone in the bus knows he's not infallible. He also mistakenly thinks Kamiyama is out to get him, as being boss of Class 1 has gained him a lot of enemies.
Note, there are two references to this manga in the anime series, based on how Kamiyama ended up in Cromartie, plus his one act of delinquency. So getting this and the first DVD is essential, and you don't need to have a tough nickname, have a lazy swagger, and menacing glare to enjoy this manga.