First you spawn as ANY character in the classic mode then kill enemies to get money to open a crate, if you don't get a common item then its not a Bustling Bungus (Big Sad) If you have the artifact of command this could be made much easier. If you don't have artifact of command then open crates until you see the beautiful Bustling Bungus. But with artifact of command, you can just simply pick Bustling

You want to obtain it because uhhhh BUNGUS Thanks for wasting ... I MEAN WELL SPENDING your time on learning how to get Bustling Bungus