Or the captions under the illustrations. "Ork weapons are extremely crude and prone to misfires or jamming." note Maybe true, but it's hard for an axe to misfire. "Tyranid weapons are formed of living tissues,note True. they often fall apart." note Not true. "Eldar technology is antiquated,note Technically true. Eldar craftsmanship is inferior to our own."note Haha, no. "Beware the tau - they'll sacrifice your babies to their gods!"note The Tau are the only major race with no measurable Warp presence and, therefore, no chance of gods. Although they may very well still sacrifice babies.
"...Try to manoeuvre around behind [the sentry], using cover as explained in Section 9. Recite the Litany of Stealth (refer to Emperor's Benedictions) to decrease your chances of being heard. Creep up behind him..."
The section on hull breaches in space vessels. A picture captioned "Emergency procedure if blasted into space" shows a drifting Guardsman trying to hold off the vacuum by covering his nose and mouth with his hand. Better than nothing?
Actually, it's worse than nothing. Holding your breath would cause your lungs to rupture from the pressure. This only makes it more fitting with the theme of the book.
It might actually be intended to kill them more quickly.
The lower half of Page 56 is a blank square with the words "KEEP THIS SPACE CLEAR. DO NOT DEFACE. ON PAIN OF DEATH"
This is especially amusing when you realise that there is a mark printed on every single copy, that would be the punchline. Even more amusing is that a friend of this troper has a copy that mis-printed the mark on the opposite page, so his space is not defaced.
In order to keep the horrors of the warp secret from normal soldiers only the major edition has a page on them and is cleverly hidden in case troopers do manage to get ahold of the book-it's printed upside down.
"If you allow yourself to be killed and ingested, your soul is forfeited."
Note that the Guard are well aware of how useless this "information" is; in the novel Fifteen Hours they are shown noting that the only thing that the primer is good for is as toilet paper!
And in Ciaphas Cain, Guardsmen on the way to a combat drop are mentioned to be "reading their primers for inspiration or amusement".
This book also contains the punchline from brick joke started in one of Dan Abbnets Gaunts Ghosts series where a soldier refers to the manual for help in his current situation to find the advice it gives is "If in doubt, move forward."
"When bayonetting an oncoming foe, thrust firmly into the throat or chest. To ensure the foe is dead repeat the procedure several times."
Considering some of the things that Guardsmen have to fight, this is actually sound advice.
The two sections that have been updated by taping the errata over the old text so that a bit of it is still readable:
Sanctioned psykers are a necessary evil that should be treated with equal respect and suspicion, where the previous advice ends "...feel no pity! Exterminate without remorse!"
"There is no such thing as an honest alien breed, but the tau are more dishonourable than any other." ("...potentially intelligent species.") [Paragraph about the tau using propaganda] "Remember: the tau lie and have no words for 'honour' and 'truth'." ("...could be negotiated with.")
There's the description of the Ork Pulsa Rokkit from the Apocalypse Reload expansion, which describes the warhead as a device that "generates and unstable forcefield bordering on contradictory physics... The orks like to encourage [its] destabilization by loading it into a missile and firing it at the enemy."
It was erased by newer editions, but one of their weapons were bombs that were guided by enthusiastic Snotlings, Doctor Strangelove style. Snotlings who'd only realize that there was a little problem with that plan when the bomb was almost hitting its target. (In newer editions, said guidance is now provided by Grots.)
The only thing more funny than Ork fluff is playing as an Ork, provided you're the sort that isn't overly stern, just happy leaving things up to the fickle hands of fate (and the dice gods). Rolling out dozens and dozens of dice for a single round of attacks alone can be a hysterical thrill if you get enough to do them all at once, and just seeing the mind-breaking (and often expensive) Kustom Konversions to models is equal parts funny and awesome; while far from tournament legal, imagine a Tonka Truck bulldozer with a "salvaged" Leman Russ cannon glued to the top and various spikey bitz all around... Oh and painted red to go faster, of course.
Then there's the story of the ork Warboss who entered the Warp, came out before he entered, and then tracked down and killed his past self because he wanted two copies of his favorite gun. The ork army was so confused that they called off their WAAAGH!. Just to make this clear, the orks are a species that exists off of Insane Troll Logic and they were still confused by this happening.
"The profoundly deaf Grot gun-crews utilize crude sign-language to communicate. This tends not to work very well, as Grots can only carry so many signs."
Ork ships in Battlefleet Gothic can be equipped with Grot Targeters, which replace images of enemy ships with images of Gretchin. This actually improves the accuracy of their gunners, as every Ork has learned from a young age how to hit Grots.
The Night Lords Novel Soul Hunter has First Claw marine Cyrion is a Deadpan Snarker of such magnificent quality. During a deployment to besiege a Forge City, the squad leader Talos suffers a seizure and psychic vision and they abort their drop til he recovers. When the Exalted demands that they go into battle, Cyrion sarcastically comments that the Squad Gunship is still available and the Exalted can use that if he wants a closer look.
From the Dark Eldar 5th Edition Codex: "Asdrubael Vect tricks his would-be rival Archon Kelithresh into opening a casket that has ostensibly been presented as a tithe. Held precariously in the collapsing field of the casket is the unstable essence of a black hole. Kelithresh's entire realm is plunged into a yawning, howling, vortex."
Pretty much any way Vect gets rid of his enemies. The death of High Archon Kraillath, killed by a "stray blast from a dark lance". "Stray" blast from a dark lance.
Roboute Guiliman's criticism of Alpharius' slow but frighteningly effective tactics.
"It's a waste of time, manpower and the Emperor's bolter shells".
Anything that involves Trazyn the Infinite, such as his "thank you" letter to an Inquisitor for "gifting" him five regiments of Guard.
He replies with an equally interesting gift, a hypercube that is "fascinating, if you can escape from its clutches."
He also casually talks to Ultrmarine Captain Sicarius about how he was "old friends" with Guilliman and plans to steal his body from Macragge because his gallery is a better place for it.
One story from the Fifth Edition Tyranid codex goes that one day, a Tau colony was facing invasion from the Tyranids. The situation looked hopeless, until the Necrons unexpectedly appeared from the colony's moon and destroyed the Tyranids. What does the Ethereal in charge of the colony do? He throws a party to celebrate their "rescue", and then decides to greet the scary metal skeletons with a grand welcoming ceremony when they come down to visit. You can guess how wellthatwent.
Even better since it happens a few days after the celebration started.
The Farsight Enclaves supplement has one in which a Tau Battlesuit during the Battle of Dal'lyth confronts an Apothecary from the Hammers of Dorn Space Marine chapter. Said Battlesuit quizzes him about what he's doing (extracting Gene Seed from fallen Space Marines), blasts a group of Marines trying to sneak attack him, then salutes the Apothecary and jumps away to carry on the battle. The Apothecary's reaction?
"Captain Rumann? When this is over, we need to talk".
During "The Trials of Azrael" the titular Azrael fights Kharn the Betrayer, during which, Azrael proudly declares himself to Kharn as the Supreme Grand Master of the Dark Angels. Kharns reacts:
Kharn (Totally not impressed): "Of course, that ridiculous helmet should have given you away".
This image◊, which sums up the Dark Eldar perfectly.
In the first major codex for the Necrons, there is a hilarious outcome to a short story where a Callidius Assassin attempts to kill a target who has already been killed and replaced. By the C'Tan Deceiver. It promptly No Sells her attack, absorbs her sword, then sucks her life-energy just for kicks.
Apparently the Deceiver likes the spice of Polymorphine on human souls.