Isaac Hayes and Dionne Warwick were once a secret soul supercouple. The Shaft hitmaker recently revealed he and Warwick, Whitney Houston's cousin, dated in the 1970s. He says, "I went out with Dionne (for) about six or seven years. We'll be friends for life." Ironically, both stars had big hits with Burt Bacharach's ballad about heartache, Walk On By.