He first did the "beep, beep" noise in the Warner Bros. parking lot as a polite means of telling people to get out of his way. Paul recorded several versions of this, and sound-engineer Treg Brown sped some of them up and looped them together. These recordings were ultimately used for the Wile E. Coyote & Roadrunner cartoons. However, Paul was uncredited for his work, as Mel Blanc's contract with WB stipulated that he was the only credited Looney Tunes voice actor.