The viral video Hiruma makes in Chapter 53 to get the Nasa Aliens to play the Devil Bats. It involves depicting the Aliens' racist coach as a (literal) chicken and putting him through a Humiliation Conga. The build-up to it makes it even funnier, as you just see Hiruma filming random things out of context (from Monta doing one of his acrobatic catches to Cerberus taking a crap) and have to wonder what he's up to this time.
Sena's delirious, exhaustion-fueled hallucinations after the game with the Nasa Aliens. Especially when he sees a shirtless Shin carrying a huge dumbell, a ten-ton weight, and a live elephant. Balanced on a fingertip.
Sena: He can't be real! But the scary thing is, I can't be sure...
During the game between the Koigahama Cupids and the Seibu Wild Gunmen, Hatsujou is about to go through his usual shtick of making fun of the opposing team for not having girlfriends to cheer them on... and then he sees Seibu's cheerleaders, and laments "Oh no, it looks like we've lost on every count!"
When two panels show "before and after" to highlight the change that the three have gone through.
Kurita: "Well, one person hasn't changed a bit..."
Bonus points since in the Anime, rather than it being a close match the entire festival, Hiruma's team swept them away. During the "3 legged costume race" (Which turned out being anything but that,) It looks like Sena is going to win, until Hiruma shows up on one of Zokugaku's motorcycles.
Hiruma: "It's only natural that the bunny would be faster than the turtle. Kehehehe!!"
Hiruma: *Pulls out a gun*. "I'll shoot you if you run ahead of me, my fucking forest friends."
Kurita: "HAAA! THAT'S A SCARY BUNNY!"
Everyone: "There's no question who's in there now."
This. Take particular note of exactly who Kurita crushed. Two of them are Devilbats.
Kotaro Sasaki using up one of his team's time-outs... just so he can tell the Devil Bats the Bando Spiders' dramatic back-story.
After the Bando game, Hiruma decides to punish Musashi for leaving the team by... giving him a haircut. Of course, this being Hiruma, he decides to go with the most ridiculous hairdos ever, including at one point a clown afro. Bonus points for Hiruma's increasing laughter, Kurita looking mortified, and Musashi remaining stoic the entire time.
The quiz show at the Ojou Academy school festival. Highlights include poor Sakuraba getting partnered with Ootawara, Ootawara and Natsuhiko's "idiot battle", and Mamori's startling knowledge of the ingredients of her Trademark Favorite Food.
In the end, Sakuraba and Ootawara end up dead last and are forced to spend the rest of the day in maid outfits... including during football practice.
Or, during the game against Deimon, Ikari gets fired up and starts pulling on his chains... then he finds out one of them belongs to Cereberus. What follows? Ikari vs. Cereberus. The dog wins.
Juumonji: "Cereberus! Get out here and stop the Ballista!"
In the Oujou vs Devilbats competition, after finally managing their first touchdown, Monta claps his arm over Sena's shoulder declaring that they'll plow through to the next touchdown with an unbeatable tag team. Sakuraba hears this and tells them that he and Shin will do the same and score as a tag team. The commentator notes that Shin isn't the type to put his arm over someone's shoulder and wonders what he'll do.
After Kurita finally manages to stop Gaoh, the rest of the team gets fired up resulting in....ultra-manly screaming and thick eyebrows. Even the mascot. This troper nearly choked laughing seeing Marco's reaction.
The girls had to resist that moment with all their heart...
Gaou + Agon vs Gomery and the pages building up to it, starting from Agon getting his hair shaved off, were absolutely, gut-wrenchingly hilarious. Sena and Monta put it best.
Sena: "The worst. It's the worst tag team in history."
Monta: "From the bottom of my heart, I'm happy they're our teammates."
Special mention goes to Mamori, Sena, Monta, Kurita, Suzuna and Ikkyu's priceless reactions when Gomery shaves Agon's hair.
Sena: "Out of all the players...the one he shouldn't have laid a finger on..."
Agon: "Hey, I thought I'd try and pretend to get along with you bastards, for the sake of the three million, but I've changed my mind. I'LL GO AT FULL STRENGTH AND MAKE A BLOODBATH OF THESE BASTARDS!!"
Also Taka's completely stoic "I'm glad I wasn't walking on that side" comment.
The night before the match with America, the whole team bursts onto scene screaming bloody murder which builds to be....
Sena: "What's with that uselessly badass pillow fight?!?"
Sena nervously asks a few people if they could make some room for them at a resturant. They rudely make fun of him. Enter Gaou, Shin and Agon. Shin politely asks, Gaou has a Slasher Smile on and Agon flat out tells them to "die".
Anytime the normally stoical Shinryuuji Nagas (minus Agon and Unsui) start blushing, hooting or hollering whenever they see a pretty girl. Only to later revert back to normal when they see guys.
Mizumachi is more concerned with how Agon's hair regrew in such a short time and suspecting it was a wig when everyone else was freaking out over how Gaou had gotten easily beaten by Mr Don. Next panel...
The tiny Chuubou sending Gaou flying through the window. Sena's reaction is priceless. 
Or, during the game against Russia, Gaou is looking forward to fighting Rodchenko, since he has the most strength in the World Cup. When Chuubou manages to take him down, Gaou gets another idea...
Marco: "Aaah... Gaou has switched his target. My condolences."
Rodchenko was heavily hyped by the powerful linemen of team Japan as a powerful opponent, being a Gold Medalist for Weight Lifting and World Record Holder for benchpressing. After Chuubou takes him down, Gaou has a shot at Rodchenko...and easilyswats him aside with one arm.