Doonesbury by Garry Trudeau for February 09, 1973
Transcript:
Man: You're the new D.J.? Mark: Yeah, Roger asked me to drop by. Where's the studio? Man: Not so fast. You got any experience? Mark: Hey, mammas and daddies! Unwind your minds and rethread your heads! Pappa soul gonna lay down some riffs to make groovin' behoovin'! Man: First door to your right. Mark: Beautiful.
Without reading ahead, I’m guessing college radio.