You can be a true nerd without reading Watchmen, though there is a good chance you'll be berrated for boasting about this lack of knowledge. Sometimes, it's just easier to fake it, since reputable nerds lie about reading comic books all the time. The most common comic books people lie about reading are often superhero stories, comics with a movie or TV show to compliment the narrative, or comics that are too deep to dive into over the course of a single weekend.
From Marvel's Secret Wars to DC's Killing Joke to independent properties such as Ghost World, the comics that make the nerdiest nerds into frauds are also some of the best graphic novels on the market. Although you can usually get away with pretending to read Sandman or Doom Patrol - considering most people conveniently don't want to discuss specifics any more than you do - there is a reason these comic books are ranked among the greatest of all time, and it might just be worth your time to actually dive in.