If you haven't seen Katy Perry's new "Birthday" video, you're in for... a lot. It's Katy disguised as five different horrible birthday entertainers (a clown, a facepaint-unsavvy princess, an animal trainer, a hacky bar mitzvah performer, and an elderly stripper) and ostensibly ambushing real parties full of people who don't recognize the pop star underneath the makeup. She's purposely a wreck in every incarnation, and we marvel at the wild reactions from partygoers who can't believe an old stripper would collapse on the floor or that a clown would be so terrible at making balloon animals. 

Opinions about the video are mixed even at HitFix, but I think the attempt at bawdy humor in this video is truly what separates Katy Perry from the similarly irreverent Ke$ha: Katy pretends to go all out and Ke$ha actually achieves it. 

Perry is no stranger to silly getups. In "Last Friday Night (T.G.I.F.)" she donned braces and headgear to play a nerdy teen who can't remember what happened at her house party the night before. She play-acted the role well enough -- and she shows comparable verve as the pet trainer character in "Birthday" -- but something about Perry's vaudevillian flair doesn't work because she is always poking fun at someone, laughing at these characters as opposed to inhabiting them and making fun of herself too. Watch as she struts around as octogenarian dancer Goldie in "Birthday" and requires a defibrillator once she falls to the ground. Is this not just ageist humor masquerading as an exhibition of Katy's bravado? What is funny about watching an old woman collapse at a "real" geriatric birthday while onlookers look on puzzled? Is it supposed to be funny that she's sexual? That most of her breasts are exposed? The joke is an ancient, tired one but we're supposed to give Katy props for having "gone" there, and that's where this video fails most: It wants to be silly but its self-congratulatory callousness is serious. 

Plus: Too much of this is plain gross. You could say I Avril'd in my mouth when Katy attempts to grind with a "real" partygoer at the bar mitzvah. Ever since I realized that Katy Perry really wrote a song called "Lemonade" that goes "Milk / milk / lemonade / 'round the back's where chocolate's made," I've been weary of her winking vileness.

But back to Ke$ha: As far as I'm concerned, the best video in recent years to succeed as a standalone statement of comic weirdness is "Blow." Sure, the opening dialogue is baroquely obnoxious, but that's also the point. She's in charge of every bizarre moment in the video, never seems to plead or care for congratulations, and she's not afraid to look like a true ass as she duels with James van der Beek or exchanges glances with a unicorn. She's trashy and knows it. It's hard to criticize someone whose career is based on delirious, purposeful self-deprecation like Ke$ha's, but it's right to criticize someone like Perry who plays for the same effect but settles for condescending coldness.