Bikini-clad students attend college summer school on a Malibu beach, where music and fun in the sun dominate the curriculum. Clean-cut teen dream Rick Nelson played the Dean of Drop-Ins, who each week welcomed singers and other celebs as `guest professors.' Among them: the Four Seasons; Engelbert Humperdinck; Leonard Nimoy; Bobby Rydell; the Doors; and Marvin Gaye.