EDIT: Guys, seriously. This is a joke thread, if you want to complain about sprint, loadouts, or whatever, there are literally hundereds of threads you can do that in. Why you feel the need to complain about them here is beyond me.
-Legendary ending actually shows Masterchief waking up in cryo, and realising all the events of Halo 4 were a dream.
-The third grenade type is actually not a grenade at all, but a disco ball. When thrown, it starts flashing, and Rick Astley’s “Never gonna give you up” begins to play across the entire map. Spartans within the area will drop their weapons and begin dancing. Effect lasts until the end of the song.
-In the campaign, Whenever you kill an enemy, Cortona will appear on your screen (just like in Halo 3) to congratulate you on a job well done. Combat does not stop during this time.
-The BR is pink for no apparent reason.
-To promote teamwork, whenever a teamate dies in MM, your character will break down on the ground and begin sobbing uncontrolably for 5 minutes. Also when you get an assist, you and the player you assisted must have a celebratory high five.
-Justin Bieber replaces Jeff Steitzer as the multiplayer announcer.
-The final boss battle features Masterchief and the ancient evil agreeing to a kinect based dance off.
-Instead of a Warthog run, Masterchief must navigate the level on a tricycle.
-In 4 player Co-op, players get to choose to play as either Masterchief, Misterchief, Chief or miss chief.
-Whenever your shields go down, your character shouts “I’m in trouble!”, whenever they recharge, he says “That was a close one!”. Every. Time.
-Warthogs are replaced with actual warthogs.
-The competitive single shot weapon 343i mentioned is actually the rocket pistol from the trailer.
-You asked for a better legendary difficulty and 343i heard you. Your arsenal for legendary now consists of a paintball gun and some pepper spray.
-All cutcenes will now be flash animations.
-In order to prevent the player from getting bored, commercials will now be played during the main menu, respawn screen and pre and post game lobbies.
-To help show Masterchief’s human side. All the missions will be flashbacks from his journal, and everytime a marine dies, he will rock back and forth in the corner crying deeply for 15 minutes.
-To save time, the second half of the campaign was made in forgeworld.
Best community ideas:
-every map in the game has a mancannon like narrows, but also fall damage like reach’s multiplied by 10
-sometimes your rifle backfires and explodes, which results in instant death
-if you betray a teammate that has a power weapon, said weapon will have infinite ammo and 2x damage
-if you get 10 kills in a row you can call in a banshee chopper gunner, at 25 you can activate the Halo rings
-the laser can now fire through objects
-All grenades are replaced with Pokeballs.
-Every time you jump, you have a 20% chance of falling and breaking your knee, in which case you have to recuperate for 5 hours.
-Elites in MM are replaced with Barney the Dinosaur in different colors.
-Your Warthog is replaced with a Worthog, which is just an Elite making car noises.
-When you complete the campaign you unlock the ability to see through your visor.
-Every time you swear through your mic an enemy will stop attacking you and wash the Chief’s mouth out with soap.
-Grunts now have an Austrian accent.
-Shield recharging is a preorder DLC.
-The ancient evil is the Arbiter with an evil laugh, a dark cloak, and a random cat that he strokes whenever he talks about his evil plans for world domination.
-The new Recon helmet is now a knee-pad with the words “Believe” on it.
-Whenever the Chief is hit by ANYTHING he collapses to the ground and starts doing yoga.
-Cortana is replaced with elevator music that plays the next objective to you in song.
-Everytime you kill an Elite his wife bursts out crying and screaming WHY??? and you have to attend the funeral in a white tuxedo while Cortana is crying in the background.
-One of the custom loadouts includes a Teddy Bear as your primary weapon, Hope as your secondary, and the grenade is filled with confetti.
I will be updating this thread with new ideas as they come to me, as well as ones from the community, so feel free to make up your own 
