I can't imagine what goes on around here in the dead of night, so one night last week I snuck in with my spelunker's headlamp to find out.
Billy Jam of The Hip Hop Slam was on the radio, hosting Bring That Beat Back, and he was curious to find out what the rest of us had been up to all week. So he went into WFMU's Most Recent Archives page, and he played back the first few seconds of everybody's show. Mind you, Billy was on the air at the time. Here's the playlist evidence, and here's the mp3.
Turns out this wasn't the first time Billy had used his unwitting compatriots in the service of the radio arts. Several weeks prior, he didn't feel like back-announcing his sets -- so he grabbed a bunch of mic breaks that had already been accomplished, by others, concerning entirely other things. That evidence is here. God knows what else lives inside those archives, go find out for yourself.
I can't readily recall many other instances of WFMU DJs using other WFMU DJs for their own (radio) ends, though surely Kenny G has been present in some experiments, either as victim or perp. His show has been hijacked more times than I can count, some of which he still doesn't know about! For now, you want to get your WFMU DJ Manipulations on the radio, you gotta stick with Billy Jam.