My too obvious answer is the entire Gathering Of The Juggalos segment w/ PFT, which had me wheezing in my cube at my former job.
Another one that comes to mind was from the epic Bruce Springsteen biographer call from late last year. As I walked down the street, I listened to the real story behind Darkness On The Edge Of Town, bursting into laughter on a crowded street corner when I learned that the main characters, Rip and Mary, didn't have the means to start a family b/c Rip was "born without nards." It came out of nowhere, and Tom's attempts to quickly move the call forward just made me lose it.
Of course, my laughter was amplified 1,000 times later in my walk when the biographer sang the original lyrics to "Racing in the Street". What made me double my pace so I wouldn't have to be around one single group of pedestrians too long was the gem of a lyric, "I got those at the Car Quest also downtown...because they were on sale there."
Later, a friend sent me a link to a Bruce message board and a post dedicated to this particular call.