South Park - Season 15 Episode 9 -

During a game of border patrol vs. Mexicans, where the kids play the two groups, Butters goes missing and eventually winds up in Mexico where he becomes their new leader, Mantequilla. Suddenly legal and illegal alien Mexicans flood back across the border to Mexico for a better life because of the decline of the U.S. economy. Eric joins the U.S. border patrol and squares off against Butters.