There are so many delightful angles from which to attack this idiocy. I'm positively bubbling.
The primary focal point of stupidity here is the fact that most of Sesame Street's audience still breast feeds. They see titties all the time. And when they see titties, they don't think "fun bags" or "dirty pillows," they think "food." So really the worst thing that might happen is Katy's cleavage might make the tots a bit peckish.
(Ok, to be fair, the absolute worst thing could be that the sight of her breasts might cause a feeding frenzy where all the 2-year-olds storm the television set, trying to reach her luscious rack, and begin licking the screen so vigorously that they cause a short circuit that cuts off all electric power in North America, at which point Iran and North Korea coordinate a perfectly timed attack against the United States and the world's last hope for freedom and justice is gone forever. Worst-case scenario.)
A secondary tidbit of stupid is the fact that, cleavage or no cleavage, Katy Perry is probably not the role model you want for your kids. Katy Perry shows her tits everywhere. Even if she wore a habit during her Sesame Street debut, if your kid ends up liking her and wants to see more of her, the first thing the kid's going to discover is that her breasts are *everywhere*. That, and they would also start singing "I Kissed a Girl" on car trips.
I'm not even bothering to address the underlying prudishness and fear of sex that is really behind all of this inanity, by the way. Never mind that your kid may *want* to grow up to be a sex-pot pop star. Never mind that it's perfectly normal and healthy for women and girls to want to be sexy. Never mind that the primary purpose of boobs is to give men something to look at while they listen to women talk about feelings.
Let's pretend that sex really is scary and wrong and children need to be shielded from it for as long as possible. Even so, no kid watching Sesame Street is going to associate Katy Perry's ta-tas with sex, because no kid watching Sesame Street even has an inkling of the concept of sex or sexuality. Not even the ones who masturbated as infants, or who walked in on Daddy donkey-punching Mommy the other night.
You know who will appreciate the tittalidge? The adults who are forced to sit through mind-numbing hours of Teletubbies and Barney every day. For them, watching a busty pop icon bust a move is a breast, er, breath of fresh air.
Children's shows have long had hidden messages for adults. Watching Looney Toons as an adult is like watching a completely different show. I recently saw a cartoon on the Disney Channel that referenced Joseph Conrad, for Christ's sake. It is not now, nor has it ever been, completely about the kids.
I think it's about time that we, as a culture, owned up to this fact and moved toward a better integration of children and adult entertainment. Forget having Katy Perry guest star, give her her own show: "Learning to Count with Katy Perry in a Bikini." Imagine if 26 Victoria's Secret models taught you your ABCs. I bet you'd learn right quick. And there's really no reason why you couldn't remake The Little Mermaid with Prince Eric shirtless the whole time.
Lots of love (and boobies),