Teen girl squad makes me laugh. Hard. I don't know if it's the girly voice Strongbad uses or the randomness of it or the very creative ways the main characters always die. It's probably that last one...because death is hilarious.
One time Matt recorded the audio from an episode and texted it to me like 5 times in one day. That was a really good day.
Here's a favorite. Valen-times Day. The fruit cup thing makes me snort every time.