Herpderpes is a sexually transmitted case of stupidity, symptoms of this include general herping and derping, and is not limited to brain farts and mind queffs. Can be extremelycontagious during the early onset of the disease, and has no cure.
A Herpderpington is an individual who enjoys photobombing people's photos by making the typical Herp Derp face (or equivalent). This can either be done as a joke to be funny, or done to be an asshole. Usually, Herpderpingtons act as a group, so the name comes from a play on words on a family name or last name.
It is also the official title for those who herp derp.
Some of my friends were photoboothing before class when suddenly the Herpderpingtons photobombed us.. but the picture ended up being really funny!