The master of events, Violet CLM. And the semi-master of events, Ninja Dodo. Had helped me write my JCS Event list, I have filled in some of the blanks, but yet there are still unknown ones.

There are 3 lists here: Unknown Events list, Unconfirmed Events list, & Discovered Unknown Events.

This questions has plagued JJ2 since 1998 when JJ2 was made. Now the question is answered.

Unknown Events (In order from Enemies-Pickups)
Beeboy-Swarm Enemies-Bad Guys
Dim Light Environment-Lighting
Set Light-Flicker Environment-Lighting
Leaf Environment-Objects
Sucker Tube-Trig Sample Environment-Objects
Fire Envoronment-Scenery
Lava Environment-Scenery
Area ID-ID Gameplay-Area
Tests 1-6 Gameplay-Area
Belt Left-MCE# Gameplay-Modifier
Belt Right-MCE# Gameplay-Modifier
Slide Gameplay-Modifier
Ambient Sound-Sine Gameplay-Sound
Jazz, Lori, & Spaz Start PositionsPos. Gameplay-Start Pos.
Gem Ring-Speed & Length Pickups-Gems
Autofire Pickups-Powerups
Gun Fast Fire-Type Pickups-Powerups
Max Weapon Pickups-Powerups
Laser Shield Although this JJ cheat code works (type 'jjshield' 4 times in SP mode, not CO-OP!), the event does nothing. Pickups-Shields

Unsure Events
NOTE: These event options are unsure of, they may have a purpose but when I talked to Violet CLM about them, he said they didn't do anything, or were not sure abou what they did.

Buttstomp Scenery-Empty, Empty, & Empty Submitted by VioletCLM: One of them lets it be used for MCEs, but the rest (as far as I know) don't do anything. Gameplay-Triggers & Scenery
Collapsing Scenery-Empty Submitted by VioletCLM: The parameter does nothing. Gameplay-Triggers & Scenery
Destruct Scenery-Empty Gameplay-Triggers & Scenery
Destruct Scenery BOMB-Empty, Empty, & Empty
Hor Blue, Green, & Red Springs-Empty Submitted by VioletCLM: This does usually nothing, but it may do something when made with an MCE. Gameplay-Triggers & Scenery

Unknown events, that have now been discovered
Addon Dog Submitted by myself: A baddie only for TSF. This baddie is invisible tall and undefeatable, he can’t be killed. It also doesn’t move. Enemies-Bad Guys
Addon Spark Submitted by myself and others: A weird baddie that is a dog-like cat, only for TSF. Enemies-Bad Guys
Bees Submitted by VioletCLM: They're an invisible enemy that generates so fast that you can have a sugar rush and it just bounces you up and down. The first time they are destroyed, you get 100 points, but after that no points. Place them on a tile of ceiling or wall spikes to make them work. Enemies-Bad Guys
Butterfly Submitted by myself: An invisible enemy that doesn’t move and can hurt you if you touch it. Enemies-Bad Guys
Tweedle Boss Submitted by VioletCLM: This boss does nothing really. But combine him with the Devan (Robot Boss) event to create the Jazz boss, this boss has no next level and music option, so this boss is really just for show, and not for play. Enemies-End Bosses
3d Spike Boll-Sync Submitted by Black NInja & Violet CLM: Type a number here, up to 3 to adjust how long the 3d Spike Boll will wait before swinging. Environment-Objects
ADDED NOTE: Sucker Tube-X-Speed Note from VioletCLM: For diagonal sucker tubes, set the X and Y speed to 20 (or -20). It will send you in a diagonal combination of those two directions. Also, diagonal sucker tubes going left/right and up will start out going diagonally, but end up going straight up. Environment-Objects
Area ID Submitted by myself and others: Use this event with the Rocket Turtle boss to control the Rocket Turtle. Keep placing Area ID’s to make the Rocket Turtle follow each of them, the turtle will not follow the same area ID more than once. Once the turtle is on an ID he’ll be there practically forever or if it’s the last ID then he’ll stay there. It’s really only useful with the Rocket Turtle. Gameplay-Area
ADDED NOTE: TNT Ammo+3, and on a certain condition Gun Barrel & Gun Crate Submitted by myself and others: This weapon does 0 damage in MP mode, truly it's only good for confusing Newcomers, using it on triggered blocks, and killing baddies. If a person in MP mode has 1 heart and you successfully kill him with TNT then you won't receive the points. Even know TNT does no damage, this actually can happen sometimes. Pickups-Ammo
TNT Powerup Submitted by myself and others: Yes, the TNT Powerup does damage, and unlike his predessor the TNT ammo, this actually deals 1 damage in MP mode and it counts if you kill someone with it. Get this weapon by blowing it up with TNT. Pickups-Powerups