The Big Merman

Phineas and Ferb make a Phine booth that can change people into Mer-people. Ultimate uses It (With Phineas's permission) so he can understand If life under the sea is as great as the sailors say they are. Meanwhille Khaka Peu Peu tries to be a member of L.O.V.E.M.U.F.F.I.N, but needs to take a qualification class to be certified