At their best, Young-Holt Unlimited created some of the best instrumental 1960s fusions between soul and jazz. "Wack Wack" is one of the best of their tracks in that vein, and one of the most successful, making #40 in the pop charts and almost making the R&B Top Ten. "Wack Wack" is a simple, even silly tune, like an extended vamp on the high-energy lounge soul-jazz that Young-Holt Unlimited's ex-employer Ramsey Lewis had employed. It's performed with a knowing, sly hip groove and exuberance that transcends its relatively basic melody. The cut starts with pretty explosive cool jazz drumming by Red Holt, periodically emphasizing one or two hard taps, as if to mimic knocking on a door. A distant chuckle then precedes the "vocal" part of the instrumental, which is just the trio half-singing, half-barking the words "wack wack" in time with the hard drum taps. Though the basic bluesy chord pattern is so simple as to be cliched, the suave yet swift rhythm is dynamic, leaving room for bluesy stop-start piano and standup bass trills at the end of the verses. On subsequent verses, bouncy piano and scatting instrumental bass take their turns at the front, with some very distant hipster hum-scatting heard in the background. At times, a zooming standup bass and drum rolls take the brief "solos" that punctuate the end of the verses. The scatting vocals reappear ever so briefly in the final measures to restate the nonsense title "wack wack," bringing the track to a sudden cold ending.