It's a nickname I gave George S. Welch, the fighter pilot. He and Kenneth Taylor shot down more planes than anybody else at Pearl Harbor, partly because they took off from an out of the way airfield and had the P-40. Welch then served in the Pacific Theater in the P-39 and P-38. Dick Bong said that if he could shoot like Welch his score would have been a 100 already.
Welch did break the Sound Barrier after the war, and Officially it was recognized a few months late after first letting Yeager get the honor of breaking the sound barrier first. Now some people near to him and ground crew at his base say that Welch broke the barrier before Yeager. Twice. Once like 15 minutes before him! It's possible, because he was using F-86 Sabre to break it in a dive. Yeager does get the honor of breaking the barrier in level flight, since Welch couldn't do that.