My super-pedantic grammar sense tells me that your (possessive pronoun) grammar is incorrect. What you meant to say was:
When you're the only person in the room who used the DynamicSteemians tag
That's me in the meme/pic pointing at the mistake! :)
You saved me from making the same comment. It's easy to make this typo, but why go to all the trouble to create a meme without proofreading just a few words? Just in case it isn't obvious: YOU ARE = YOU'RE and NOT YOUR!