Watched “That’s My Bush!” on Comedy Central Wednesday night. (Wednesday? Feels like three years ago.) While I understood and admired what they were trying to do, I missed the slyness that underlies the grossness of “South Park.” One interesting thing was, 90 percent of the show as presented could have substituted Al and Tipper and the jokes and setups would have been the same. I guess that’s understandable in a show that didn’t know who its main character was going to be until just a few weeks ago, but still. I know Matt and Trey want to send up sitcoms more than the presidency, but like with Series 7, it’s hard to parody a form that’s such self-parody already – Urkel, anyone? Series 7 manages it (brilliantly); TMB! doesn’t.