A Jewish Joke is a one-man show about partnerships, but that is just one of its several paradoxes. The play explores Jewish comedy, though from the serious viewpoint of its effect during the era of the Hollywood blacklist, when humor could either get a guy out of a jam, or reinforce anti-Semitic stereotypes. Many old jokes are told during the 90-minute production; however, they are delivered with such odd undertones that it is impossible to tell whether director David Ellenstein was hoping for legit laughter or uncomfortable sighs from the vintage zingers that are rife with sexism and prejudice. And Joke is a play about writing which, when it falters, does so because the script is, at times, contrived or repetitious. When it succeeds, it does so because Phil Johnson, of San Diego’s Roustabouts Theatre Company, so fully inhabits his role that his character’s stressed-out persona transcends the page.