A yell, yelp, shout, or scream someone makes in the bathroom, preferably a port a potty. Reminiscent to the Rebel Yell during the Civil War except it is a sign of good feelings or making people laugh. Coined during my baseball game in which a person yelled while inside a port-a-potty.
Tommy: Dude did you hear Jimbo's port-a-potty yell?
Bill: No but Cindy says it was epic.