Not saying we have to make any more, but if you have any fun ideas (meme categories or not) you can reply to this post

Sword%, be the first to get any sword in the game

100Damage%, first to deal 100 damage to any object.
Death%, first to die.
Kill%, first to kill any hostile creature.
Everything%, get every non powerup item.
69%, get 69 of any item without dropping any items.
InvFull%, First to fill your inventory with out spreading items to fill it.
Power%, get 5 of any power up.
Dani%, beat Big Chunk while only being able to pick up Dani's Milk.
NoPower% beat Big Chunk while not picking up any powerups first.

Just a couple of ideas that I came up with.

Full Set of Chunkium Armour

House%, make a house with 4 foundations, 1 door thing, 7 walls, a roof and a workbench.

Kill 1 of every type of enemy

collect wood idk lol

Fastest death time plz

Furnace% get furnace, and muck to everyone here
wooden tools% get all of the wooden tools
All stations% craft all of the stations in the game(workbench anvil cauldron furnace)

I have a idea for a new Muck speedrun category

Workbench%

speedrun to get and place a workbench

Rules:

1. You need to show menu screen when creating a world

2. Workbench needs to placed not obtained

3. Time starts when you spawn and ends when you place workbench

(singleplayer) can only be completed by yourself

And there can be furnace% and anvil% as well

same rules but change workbench to furnace or anvil

Go Home and Die category (based on the BotW category):
You have to find a shack and somehow die in it as fast as you can

Kill dave category (based on someone)
Kill a dave as fast and as epically as you can.

Meat%

(set seed and random)

Rules:

must show the main menu for approval of set seed or random.

kill and cook a cow then eat it as fast as possible.

Edit: this was a idea by @PaintyPPaintyP

obtain mithril% (maybe obtain iron% too?)
RSG and SSG

just obtain a mithril ingot

also an all chests%

open one of every chest type (basic, common, uncommon, legendary)

Revive a homie%

Tutorial: finish the tutorial at the start of the game

timer starts when you load in the world

timer stops when you place down the workbench

Get every Power Ups

Craft all stations RS coz SS would be so bad

armor%
get all armor pieces of any type as fast as possible
aka reset hell

Clear Statues - Activate and defeat every statue in a map. Seed is required to check the validity of the run.

just my little idea

obtain all the guardian gems