It was a double-episode and was very cringe-worthy.
The plot centered around the What's Happening gang going to a Doobie Brothers concert and the rotund character Rerun was convinced by bootleggers to conceal a cassette recorder in his clothing.
During the concert, the overly enthusiastic Rerun was dancing in the aisles like a maniac and suddenly the cassette recorder clattered to the floor, completely stopping the concert as the "shocked" Doobies looked on in acute disappointment from the stage.
The rest of the episode devolved into this overly long and cringe-worthy lecture by the Doobies to Rerun and his sad cast of friends (Dwayne, Roger, Dee, etc) about the evils of bootlegging.
No doubt the RIAA arranged for this lame appearance. In those days, there was much controversy over blank cassette tapes and the easy ability for people to record music on them that was not paid for. The average album in those days retailed for about $8.98.
This double-episode was intended to shame the nation by exposing the loss of revenue to music bands through bootlegging.
But wouldn't circulated bootlegged concert tapes produce more fans of a given band, and thus propel album sales?
We may never know for sure. But Rerun was certainly humiliated by the experience and was never the same again.