Why is this such a big deal? Sometimes it's fun to talk about other things that are funny and/or interesting and not mopeds. It's also fun to talk about these things with people who DO share a common interest (ie: mopeds). It's fun to share funny things with people that you like (ie: "Breakin' 2: Electric Boogaloo") and it's also fun to post interesting happenings/news/etc. with people you know and like.
I don't think it's even necessary to post that something is "OT" because unless you're fucking retarded, you can tell when something is "off topic". If I post something with the subject "'CONVOY' IS AN EPIC MOVIE WIN" then I'm pretty sure you know I'm not talking about mopeds.
If I post "WHAT IS A GOOD EXHAUST WITH PEDAL CLEARANCE FOR A MOTOBECANE?" then I'm pretty sure you know that I'm talking about MOPEDS.
But regardless, I <3 Moped Army, and the OT threads can lead to hilarity so keep them coming.