In order to enjoy this one you need to be a bit of a geek. You need to have seen The Lord of the Rings trilogy (which I automatically assume everyone has) and you need to at least know what D&D is and be aware of what a D&D session entails. If you meet these criteria, this comic is a goldmine of geeky humor. If you don’t, you need not even start reading. The premise is that the characters from LOTR are actually characters roleplayed by nerds during a real D&D session (with a tedious DM and everything). The comic is in fact created out of screenshots from the movie which makes it all the more fun (just pay attention to the characters’ faces). The story kicks off somewhere around the middle of the first movie and, admitedly, isn’t hilarious for the first couple of panels. But it gets better and better with each post. For bonus fun, read what the creator, Shamus Young, has to share after each panel. Most of the time it will either be genuinely useful, fun advice for aspiring DMs or a funny self-deprecating joke about D&D nerds.
Similar to this but not as entertaining: The Order of the Stick and Looking for Group are both D&D related comics which I tried reading. They were funny for a while but then the jokes just sort of ran dry and the plot took over and I guess I got bored.