'How I Met Your Mother': Watch a Preview of Katie Holmes as the 'Slutty Pumpkin'

We've seen a number of references to early seasons so far on "How I Met Your Mother" this fall, but a big one is about to come up for this year's Halloween episode.

You see, Ted has been going to the same Halloween party for years, dressed in the same costume (the always-timely hanging chad) in hopes of meeting up with the "Slutty Pumpkin," a girl who, for various unfortunate reasons, got away back in season one with no way for Ted to contact her. Yes, it's a Charlie Brown reference of sorts. It's great.

Unlike Linus' Great Pumpkin, though, the Slutty Pumpkin is actually going to appear this year. Katie Holmes will guest star on Monday's Halloween-themed episode of "HIMYM," and sure enough she's wearing that same costume, and she drops in a reference to her favorite drink (the "Tootsie Roll").

It looks like Robin is also trying to get Barney to admit that he's Canadian, and Barney is predictably overcompensating. So that should be fun.

Check out the preview clip of the "How I Met Your Mother" Halloween episode below: