It was an episode where Vinny was hosting, while Jeff was away somewhere, and using all kinds of sound effects and music. It ended, as most Bombcasts do, with emails and if I remember correctly they were crazy stories of some kind. Delivery men maybe? The week after Jeff returned with a "What the hell were you guys doing?" kind of question.
I know this isn't a lot to go off of but I'm hoping someone out there is able to take my limited clues and finds this episode so I can show it to my one friend.