We all know the type, the person who believes proper grammar must be adhered to at all times, by everyone. But a grammar nerd should really know the difference between there, their and they're - words that sound the same, but mean very different things.
One Twitter user thought he spotted a mishap, posted by Star Wars legend Mark Hamill last week.
It all started when the actor shared a photo of himself with Last Jedi co-star Kelly Marie Tran, praising her performance in the film:
SHOUT OUT to Kelly Marie Tran for no particular reason other than your more than brilliant performance in… https://t.co/BjM3xEbOPo