Doonesbury by Garry Trudeau for May 20, 1990
Zonker: Another 1989 postmark! Time to take action! Hi! Former U.S. postal service temporary employee Zonker Harris here! Have the proposed new postal rates got you steamed? Sure, U.S. Postal rates would still be among the lowest in the world, but aren't you fed up anyway? Huh? Sure you are! So why not affix these dandy 5 cent protest stamps to all your mail? What better way to send a message to your postal service? They're attractive, convenient, and possibly illegal! So go ahead, slap on a U.S. protest stamp! You won't be sorry!