Chuck Jones became a director in 1938, after Frank Tashlin had left (although Tashlin eventually came back in the early 40s). Jones is mostly known for the slapstick humor, and wordplay gags which were present in many of his classic cartoons from the mid-40s onward. But his first several shorts were more slow and Disney-like, and usually focused on cute, small animal characters like Sniffles the Mouse. "Prest-o Change-o" was the first short Jones made to feature a wacky character, in this case, the crazy white rabbit from "Porky's Hare Hunt".
Ben Hardaway and co-director Cal Dalton, went back to the "hunter chasing a crazy rabbit" schtick, and brought us a short entitled "Hare-um Scare-um". Hardaway and Dalton had character designer Charlie Thorson create a new design for the rabbit. Thorson made the character grey, and a rounder head and torso, big cheeks, and big big teeth. The model sheet was labeled "Bugs' Bunny". Because, remember, Hardaway's nickname was "Bugs". Warner Bros. merchandising department took note of this idea, and began calling the chatacter "Bugs Bunny" on certain products such as glasses and booklets.
As you may have noticed, the ending to the cartoon seems abrupt. Follow the link below to learn more about the censored ending: