All of these Rush Limbaugh billboard slogans really aren't good.
If they seriously want to mock Limbaugh in his home town, be bold about it. Use the slogan: "Limbaugh Knows Failure." Then show a giant pile of drugs. Or a stack of divorce papers. Or a draft deferment. Or a Viagra tablet. Or all of it. Billboards are large. You can fit a lot of crap on one.