You know you're terribly addicted to Touhou when your brother asks if you'll cosplay as China, and you respond with, "SAKUYA-SAN, SAKUYA-SAN! CLEANING STOP!" And he gets the joke.
And when you get your friend into Touhou so you can start a group cosplay. She really likes Patchouli. I'm not sure if I should cosplay as Koakuma, Flandre, or Cirno (for my ⑨th convention.)
When you wish your Youko and Raichu cosplay would finish themselves so you can make your Chen cosplay.
When you plan on cosplaying as Orange for Matsuricon.
When you are just about to buy a Remilia and Flandre watch on E-bay, but stop because you want to make a Sakuya watch with the numbers all jumbled up. Or when you have made a sun dial to look like Sakuya.
When you play Last World, and you keep on saying Last Word by accident.