We all have those people in our lives that know EVERYTHING. You can't have a discussion without them taking over and being the boss. If you get a fake certificate on a topic, you can have some real fun with these windbags. First, you have to find a topic or industry that you can get a realistic fake certificate or diploma for, and then you simply have to strike up a conversation with your resident expert. Of course, they'll naturally take of the conversation and try to be the expert. This time, though, you are going to drop your knowledge on the topic, even if it's all made up.
More than likely an argument will ensue, and you just need to end the heated discussion by telling your know-it-all friend that you happen to be a certified expert on the topic anImage via Wikipediad even have a diploma to prove it. If you're lucky, your friend will not believe you and will require proof. Now you get to use your fake diploma to win the argument. Simply invite your friend over to your desk or home, where you'll have your realistic novelty diploma, prominently on display.
Your expert buddy will probably be a bit humbled and embarrassed at this point. You should probably follow up and offer to teach them more about your area of expertise, just to rub it in a bit. I don't know the exact response you'll get, but it's guaranteed to be funny and just may teach your friend to shut up during conversations every now and then.