Just a handy list of all the glitches/unintended mechanics. Let me know if I missed any. Also, if you hate the names I use to refer to glitches feel free to suggest better ones. If you have found any glitches, or I missed one, I'll add it to the list.

Movement Related

The majority of all movement related "glitches" is based on the preservation of momentum. The mechanic is simple and works as follows: 1. You gain speed in a direction. 2. You keep speed in that direction by continuing to move in that direction. 3. You lose speed in that direction by discontinuing to move in that direction.

Ways to Gain Speed in a Direction: Walking, Running, Jumping, Climbing, Falling Special abilities (Broney Ross, Bronnar Jensen, Bro Caeser, Broctor Death, Trent Broser?) Shooting (Bronnar Jensen, Bro Caeser, Broctor Death) Explosions (The only known exception is Toll Broad's fire grenade which just kills you)* Moving platforms (Propane tanks, Pigs, Telephones/Radiators/Transformers, Bosses?) Destructibles (Crates, Boxes, Cages, Telephones/Radiators/Transformers, Non-explosive barrels?, Terrain?) Ziplines

Ways to Lose Speed in a Direction: Walking Special abilities (Bro Caeser) Shooting (Bro Caeser, Broctor Death?) Explosions (back-boosting) Moving platforms (back-boosting) Death Obstacles Ziplines? (Presumably if you are going faster than a zipline boosts you, you will slow down)

Zipline Running

Preserves your speed from ziplining and transfers it into running speed. Lost upon slowing down. While running, attach to a zipline and press down. Very consistent and easy to execute.

Telephone/Radiator/Transformer Jumping

Boosts you forwards at an alarming speed and is transferred into running speed. Lost upon slowing down. While running, jump onto a telephone pole with an attached radiator thing. Land slightly right of center and jump shortly after landing. If you jumped at the correct time, you will get a boost. If you are even slightly off you will likely get slowed down. Inconsistent and annoying to execute.

Propane Jumping

Break the sound barrier and have this speed transferred into running speed. Lost upon slowing down. Knock over a propane tank (or shoot one that is already knocked over). Stand on it, preferably close to the back/bottom of it. Run and jump in the direction it is travelling before it explodes. Your timing will affect your speed. Consistent, but difficult to execute.

Pig Flight

Fly on the back of a dead pig, what's not to love? Kill a pig with the melee button. Stand on it, away from the direction you want to travel. Face that direction, and start stabbing. A light button mash is enough to achieve the pig's maximum speed. Just don't miss a button otherwise your aircraft is going down. Consistent and easy to execute.

Pig Jumping

Jump off of a pig at break-neck speeds. Speed lost upon slowing down. While standing on a dead, falling pig, run and jump (Exactly the same as Propane Jumping). Annoyingly inconsistent.

Pig Running

Run really fast after making your bros some bacon. Speed lost upon slowing down. While running, jump on a pig. Slaughter the pig with your gun just as you land. Keep running. Inconsistent and difficult to execute.

Pig Catapult

Send yourself flying into the air at exactly 1 million kilometers per hour. Unsure if you can maintain speed. Perform Pig Running with Toll Broad (Flamethrower) and get lucky. Horribly inconsistent, difficult to execute, and has never gotten me where I want to go.

Minigun Flight

The most broken thing in the game. Fly around laying waste to your enemies and doing pretty much whatever you want. Lost upon landing on the ground. As Bro Caesar (Minigun), press the Melee button followed by the Special Button. Hold the special button. Timing is pretty easy to get. Requires special ammunition each time it is activated. Will not consume special ammunition if reactivated before landing on the ground. Consistent and easy to execute, but difficult to master.

Minigun Jumping

Get extra height on Bro Caesar's special ability. As Bro Caesar (Minigun), hold down the fire button. As you are shooting, press the special button. You will jump in the direction you are shooting. Height is proportional to how fast you are shooting/being pushed by recoil.

Sword Boosting

Not actually a glitch. This is just a good way to maintain the very high speeds that can be achieved during a run. As Broctor Death (Sword), use your special ability while going fast.

Boss Related

Robot Skip

Killing yourself during the cutscene that introduces you to the first robot boss will cause the screen to fade to black faster. Possible with Broney Ross (Dual Pistols), Toll Broad (Flamethrower), and Trent Broser (Rifle). Throw grenades before triggering cutscene.

Robot Skip Skip

Sometimes killing yourself during the cutscene doesn't work. This will cause you to lose time. Usually only happens with Toll Broad (Flamethrower) or Trent Broser (Rifle). Prevented by getting the timing of you grenade throw correct.

Level 2-3 ~Skip

On level 2, grab the checkpoint, enter the cutscene, pause (with controller), drop out (with keyboard), and press the fire button. At this point it shouldn't matter what you do. The glitch appears to be caused by dropping out during the cutscene and then advancing to the next level. Fun fact: The checkpoint is not required, it just the fastest way to kill you. For whatever reason, dropping out after getting the checkpoint spawns you in under the helicopter underneath the ground and drops you to your death.

Robot Fast Kill

Probably not a glitch, but sometimes the robot dies faster. This seems to be due to blowing up their missiles in their face.

Robot Skip 2

Avoiding the trigger for the robot cutscenes can cause them not to spawn. There is also a way to break the trigger so you can never trigger it. Robot 1: Kill Stonebanks before he disappears. There is pretty much only one good way to do this. Stand on top of the tall building at the start of the level, jump, and use your special. Robot 2: Still not sure what breaks this trigger, but I remember doing it one time.

Stonebanks Fast Kill

This is only really a glitch in Low%. However, there are several glitchy ways to kill Stonebanks. The easiest is with Broney Ross (Dual Pistols). Throwing sticky grenades onto the back of the moving death machine causes the grenades to stick to the air. As the machine passes, the grenades blow up in Stonebanks' face. A similar effect can occur with Bro Caesar's special ability's shockwave. This is much less consistent and more difficult to pull off. It involves activating the ability underneath the machine and having it travel up terrain and into the machine. And sometimes random things just kill him.

Drop out Related Stuff They break cutscenes. Not all cutscenes are affected the same way. There are 2 types of cutscenes: video and gameplay. Dropping out during video cutscenes freezes the cutscene. Dropping out during gameplay cutscenes can give you control of you character.

They don't like checkpoints.
Unless you game over and respawn at a checkpoint, your drop out will land you back at the start of the
level, but not always where you would expect.

That's everything I can remember anyways. I plan to make video tutorials for these eventually.

*I do not remember what effect the fire grenade has on allies. It probably does nothing.