rtah
Acronym that stands for Rooster Teeth / Achievement Hunter. Rooster Teeth is a production company that makes web-based content. They are most well known for their series Red vs. Blue and as well as RWBY. Achievement Hunter is a division of RT that makes gaming/let's play content and streams regularly. If someone says they are an "rtah fan" it just means they are a fan Rooster Teeth and Achievement Hunter.
I'm so excited for RTX! I've been an rtah fan for years, I even draw rtah fanart!
RTAH
RTAH is the codeword between Starkids. We can't tell you what it means, cause it's a codeword, but you can find a Starkid and ask him.
RTAH' 'RTAH' 'Cool ! But let's not forget we cannot spend too much time on Omegle if we want to pass our OWLs' 'Oh my God ! Hermione shut up !