Oldie, and not quite about roids, but..... here are the basics of the joke. You flesh it out.

Bartender to cowboy about horse after a couple of drinks, "Yesiree, you must really like that horse to have watered, fed and groomed him before you came in for a drink. But, just before you came in here, why did you lift his tale and kiss his ass?" "Chapped lips." "That cures chapped lips?" "No, but it'll keep ya from lickin 'em."