(bear with me on this one, because I think its kind of genius)
…whenever we met another Markiplier fan [are we Heroes or Markiplites now? I shall forever be confused. Anyway..] you gave them a high 5. Then, when they meet another Markiplier fan they also give them a high 5, which because you have already given a high 5 to the first person its like that high 5 is being transferred through the palms of your hand to theirs and then on and on it continues. Through the power of Markiplier hero high 5′s you have graced the palms of thousands of people across the globe.
Then one day. A fan walks up to Mark. This fan is from L.A. Yesterday they met and high fived a fan from Chicago who was visiting their grandparents, who had travelled to NYC before hand and high fived another fan, who had just come the airport after a fleeting visit to your city, in which they had stopped at a cafe to buy a coffee, where you were sat wearing a Markiplier shirt, and [as custom] you had smiled and high fived each other.
From city to NYC to Chicago to L.A to convention this fan stood in front of Mark. They asked for a high 5, which he graciously gave. You know what that means? You’ve high fived Mark!