When a Boomer spits/explodes on you, it releases a green slime. This is called Boomer Bile.
It deals 20 damage and slows you down. It also emits a greenish slime to cover your screen, leaving you vulnerable to any zombies that hunt you down. Pressing shift will remove the slow effect but not the slime on your screen.
A special kind of bar that resembles the sprint meter. This only appears on the objective of Anti-Virus or Infection. You start off with it on Anti-Virus, but on Infection, it shows up when scratched. After 2-3 minutes, in Infection, you will die. In Anti-Virus, you have 3-4 minutes.
If you wear a health vest (such as the Christmas or Halloween Vests) you will start off with the virus because the game deducts 1 HP (since Bugfix v51b) to accurately give health. For reasons unknown, if you wear a Golden Ribbon you will get infected even though you will be full health at the start of the match. You can't get rid of the virus, even if you heal yourself, as you are at full health. To get rid of the virus, damage yourself (like jumping off a high tower) and after taking damage, heal yourself.
This bar resides on the right-hand side of the screen. You start off with 100 energy, although the Straw Hat gives you extra.
Fire is something that you do not want to mess with, as it deals heavy damage to enemies, and even you! Upon inflicted the effect, you will take 50 damage.
Just like fire, ice is harmful to humans and zombies. As a human, ice usually isn't that effective unless you are on a rescue vehicle or being chased by a horde of zombies.
When you are an Elemental in ice form, you can press "F" and use ice to fling the player off the map. The only weapon that afflicts the ice effect is the Ice Sledge. Mr Frost also afflicts the ice effect with many of his attacks.
It's really rare to gain this effect, as it could only be performed by glitches or by the explosive gas tank on New Bloxcoast. You can also lose limbs by touching lava in Halloween Obby and Lord Pumpkin. You will instantly die if your torso hits the lava.
Losing leg limbs can also slow you down from climbing up a ramp. If you jump while going up the ramp and you don't have your leg limbs, you will get pushed back down the ramp.
Stun locked could only be achieved if you are grabbed by a Hunter, caught in a Smoker's tongue, ran over by a Van, certain environments (such as the walls in Mr Frost) and explosions such as the Grenade.
This leaves you vulnerable to zombies, in most cases. You can still use your Rambo Knife or throw your Grenade in certain situations. It could be skipped by pressing Backspace, at the cost of 20 health though. Holding Backspace can prevent all stunlock but you will be unable to jump.
If you are hit by a Snowball it will damage you by 35 HP and will cover the edges of your screen with frost.
In Open Fields, there are various abilities you can get.
The speed boost does what does it says. The egg ability shoots from the front and will stun the victim and cover its screen with eggs. The lightning effect will affect everyone but you. Everyone else will be stunlocked. Running on the grass will slow you down.