08/24/2010 05:42 pm ET | Updated May 25, 2011

Top 5 Funniest: Joaquin Phoenix, Jenny Slate, Levi Johnston and More (VIDEOS)

It's been about a year and a half since Joaquin Phoenix's hip-hop alter ego made his legendary appearance on Letterman. It must have taken Casey Affleck about that long to form some sort of narrative into the forthcoming "documentary" I'm Still Here. This week, we finally got to see the first teaser.

The prize for most original and creative video of this past week has to go to Dean Fleischer-Camp and Jenny Slate's "Marcel the Shell with Shoes On." This animated short was so genuinely funny that it didn't need any viral-friendly hook to spread far and wide around the internet. Now if only SNL would let Jenny Slate do something more like this on the show...

MARCEL THE SHELL WITH SHOES ON from Dean Fleischer-Camp on Vimeo.

Naturally, everyone's getting excited for Levi Johnston's reality-TV-sponsored run for his on-again, off-again mother-in-law's old job of mayor of Wasilla. Last week, we saw Jimmy Kimmel take a stab at working as Levi's campaign manager. This week, donated their time and expertise to make Levi his first campaign ad, complete with the slogan "Building a bridge to somewhere."

The final two slots of the week belong to two horror movies (one openly trying to be funny, the other not so much) that got in on the viral video game this week in two very different ways. First up, Piranha 3D kicked off its awards campaign on Funny or Die, with its actors explaining why it deserves to win everything. You can watch the official Funny or Die version here, or the original, longer, raunchier version with more Academy-bashing (that the Weinstein Company apparently pulled after one day) below.

In what was arguably a much more clever marketing ploy, The Last Exorcism took to ChatRoulette with a video of a girl who appears to be seductively unbuttoning her shirt (guaranteed to avoid getting "next-ed"). The terrifying transformation that follows elicited the hilarious reactions shown in this "best of" compilation. This is viral marketing at its best.

More comedy videos at: