Perhaps my favorite moment from the second episode of Gundam Build Fighters, a (legally posted on YouTube) show based on the (ultimately rather violent) Gundam franchise where kids play-fight using their Gundam toys and a sort of augmented reality system:
For a bit of perspective, this is taking place in a school facility. That dude** apparently was just permitted to wander into the place (presumably because he really wanted to watch kids play-fight with their Gundam toys), which is particularly funny because earlier in the episode another character (who is actually of the apparent age to go to this school) got into a scuffle over the fact that he was someplace he shouldn't have been.
Bonus moment: One of the main characters puts the whole show into perspective.
*For the record, the Gundam anime I want to watch which I've mentioned previously are Turn A (not available in English to my knowledge), G Gundam (which is silly but awesome but on the receiving end of Gundam fanboy hate), and Gundam AGE (also not available in English, plus on the receiving end of fanboy hate). The most recent Tomino series, Gundam Reconguista in G, is also somewhat on my list, though I think it's more like fourth. This series and its sequel, Build Fighters Try, have the benefit of being fun and being currently available for free. (Reco in G is supposed to be available for free in several places, but I've had no luck getting any of those places to let me actually watch jack.)
**Said dude is known as Mr. Ral, and is based on a character known as Ramba Ral from the original Mobile Suit Gundam. In actual fact, he's essentially a personification of the memetic version of Ramba Ral, and is also actually apparently named Ramba Ral himself, as somebody supposedly addresses him as "Ramba" at some point, and others call him by the rank Lieutentant (Ramba Ral's rank, as if I needed to explain that at this point) even though he's not a member of a military but a thirty-something Gundam fanboy.