As the word suggests, this describes how popular one is on the internet. E-Popularity is common in online forums and is based simply on how many posts you have and how many people (or fan girls) respect you. The higher your e-popularity is, the more likely you're going to win any argument... whether you're right or wrong. Also, if your e-popularity is high enough, you may even become a mod or assistant admin. Some people create websites and forums simply to increase their e-popularity. Most attempts turn out unsuccessful.
animeking: OMG, KoolKid203847 has e-popularity through the roof!
Watashi: Definitely, he's so cool, I say we make him a mod.