The Flintstones Season 6 Episode 17 The Long, Long, Long Weekend ( Air Date 1966-01-21 ) Genre Family, Animation, Comedy, Kids category. Overview "Gazoo takes Fred on a trip to the twenty-first century, including a stop at Slate Rock and Gravel Company, where Fred learns that the interest on a $4.00 loan he took from Mr. Slate comes to more than $23-million! Upon returning to the Stone Age, Fred vows to repay the loan immediately.".