in dark souls there are items you can use that basically activate the multiplayer component of the game (or, i should say, the active multiplayer component; you can still see messages from other people, bloodstains from people who've died in an area, and ghostly illusions of people currently playing without the item) and increase or change your maximum hp in some way
using this item also displays summon signs other players have put on the ground with another special item, allowing you to activate the sign and summon the other person for coop play as a phantom
another big part of active multiplayer in souls games is invading another person's world as an enemy phantom. for whatever reason, the game will prioritize putting an invading player in the world of someone else who already has at least one friendly phantom summoned, and a natural drawback of this is the possibility of a player killing all the enemies in an area (so they don't have to deal with them on top of an invader), summoning as many phantoms as possible, and effortlessly trouncing the invader for the rewards
although the normal maximum amount of friendly phantoms is 2, you can use an item that increases this number to 3 but allows you to be invaded by two enemies at once and thats kinda the joke here. its not possible to have a host player, six phantoms, and an invader iirc
add in the "tfw x" meme and you have a recipe for Humor(TM)