#1, this is one ad in one regional magazine. There will always be stuff like this, even if we don't have a "pee see" culture. It's what happens when you have a First Amendment.
But #2, what's hypocritical about saying it's okay to make jokes about some things, but not about others?
Nuns have been joked about for centuries because they have often been authority figures, and they represent a big kahuna authority figure -- the Catholic church.
There's a difference between poking fun at authority figures and perpetuating stereotypes of traditionally marginalized groups.
All that said, you're also wrong:
http://www.nytimes.com/2006/08/01/bu...=1&oref=slogin
Just one example of a "disrespectful" portrayal of blacks in mainstream advertising -- about which I'm sure you heard no outcry.