This is from a while ago, coincidentally the only new episode of The Simpsons I actually watched since several hair styles ago. Other mediums the Simpsons has denounced over the years: snake-whacking, gay-hunting, gun ownership, religious zealotry and autocratic political rule.
“Hey, that hurts. No wonder no one came to my birthday party.”
Inverted Soapbox 
Eric Alterman cited the same clip in his rather lengthy piece in The New Yorker this week:
http://www.newyorker.com/reporting/2008/03/31/080331fa_fact_alterman?currentPage=all
It’s near the bottom, but seems to indicate it was a more recent episode.