I miss Marshie/Marshy/However you spell it...
I think a great idea for a ween toon would be thus:
(toon begins with Homestar in costume with Pom Pom, he is going as Indiana Jones, complete with fedora hat holding a trick or treat bag)

Well Pom Pom 'ol buddy... looks like we're off on a 'nother adventure. Into the unknown.... to seek out our fortune and glory. We're not taking no crap from nobody... NOTHING from nobody, we're on the---
(cut to Pom Pom looking bored)
(cut to strong bad and the cheat hidden away)

So let me get this straight, the plan is to just.... JUMP Homestar and steall all his candy?

Meh (in a yeah like tone)

That's the best plan ever. Oh oh.. here they come.
(cut back to Homestar talking still)

Except them snakes... I hate snakes.
(strongbad and teh cheat pop out)

Ahh ha!!!

*bubble noises* (looks angry)

Oh crap The Cheat, you didn't tell me Pom Pom was gonna be with him!! Now take it easy there big guy we were uhh, just gonna...

*cheat noises*

Scare you? Yeah! Scare you. .......... so uhm.......... boo.

*bubbles*
(both homestar and pom pom walk off)
... then suddenly the toon messes up a little and everything goes out of whack and for a split second Marsie appears transparently through the toon and then goes away with evil laughter...

Wai-Ha-Huh-wai ... what the heck was that?

*cheat noises*
(cut to homestar and pom pom trick or treating at Marzipan's.)
... except it's cardboard marzipan

Twik or Treeeat!
(silence)

Ah-hem. I saiiii. Twik or Treeeat!
(silence)

That's a really bad costume Marzipan.

(looks dissapointed)
Then the toon messes up again and Marshie appears.
Marshie: Hahahaha... Muhahaha... you can't killll meeee... I told youuuu.... I'm going to take that...
(sucks in Homestar's candy and pom pom's too)

Sweet Cup'n Cakes!

(in the distance) .. hey thats my line.

It's like all my nightmares about marshmallows are coming true at once!
(Pom Pom goes to fight Marshie but is sucked into him through his mouth)
Marshie grows bigger and his voice gets deeper and more evil
Marshie: Muhahaha.... why don't you try some of my fluffity puffity marshmallowsss........ they're.... EVERYWHEREEEEEE
(as he says that, millions of marshmallows pop out of him and rain down from the sky)
.... everyone runs off.
(cut to everyone hiding under bubs concession stand - you can see Marshie running amok outside)

Look, I never liked the guy. I knew he wasn't all there.
(homestar is looking off the other way)

Homestar, you sure don't seem too worried about the fact that Marzipan is nowhere to be found.

Who? Oh ... right right. Marzipan. She's right here.
(gets out cardboard Marzipan)

Homestar that's not Marz-

Just let it go man. Just let it go.

I always knew I'd die alone.

Your surrounded by tons of people Coach Z... what are you talking about?

I always knew I'd die by some sort of giant homicidal food. Never thought it would be a marshmallow though. Didn't see THAT one coming. *very sadly* Dooo hooo hoooo....

What are we all doing here? Let's defend ourselves! Not just sit around waiting for the inebitable! *cocks shotgun*

Let's Hurt Somethiiiing!!
(everyone runs outside to a giant Marshie with red glowing eyes... I mean so big that he is like a 20 story building...)
Marshie: WHhhhhattt doooOOooOoo youUUuuu WANnnnANNNTTTT

Um, .... nothing. We were just leaving. .... so um...

We're not going anywhere.
(extreme close-up on bubs)

It's the end of the line for you....
Marshie comes over and sucks up Cardboard Marzipan...

OHhh Marzipann!! Noooo!!!! (crying) She was so young!!
(suddenly getting brave and angry)
I'm gonna have to put a stop to this.... Homestarrrr... RUNN
(homestar leaps into the air like he did in the old toon with strongbad in the boxing ring, but he is immediately sucked in by marshie)

Whoa. That was awesome....

*bubbles angrly*

I mean that was horrible. (sarcastically) Ohhhh crap, come back homestar, we can't live without youuu...
Marshie destroys everyone and begins sucking in scenery until the screen is white...
then he turns towards the toon and the box the toon plays in gets sucked in on itself and the toon ends with a black screen, so it appears Marshie sucked in the toon itself and you have absolutely no idea what happened.
Hahahaha.