OTP = One True Pairing – basically your ultimate fave couple, real or fictional.
For example:
Friends: “Ross + Rachel are my OTP.”
Anime fans: “Naruto + Hinata forever, everyone else is wrong.”
Me: “…still arguing about fictional couples like it’s a life-or-death decision.”
It’s basically fandom slang for the couple you’ll defend no matter what — the one pairing that just feels right to you in a story. Sometimes people even ship characters that were never actually together in the original story.