Where do آپ think Ted learned to sign?

This is just a dopey guess, but since he was quite pretentious and up himself in college, sign language is the kind of thing I can imagine him learning as part of his faux sensitive, philosophical college persona. I can just imagine him with his dorky college-Ted hair leaning up to some girl in a bar "and that's why I learned sign language. Because I care about my fellow men. Even the ones who can't hear me say I care. So I had to learn to sign it. Learning this took empathy. Dedication. Truly, actions like learning sign language are what separate humans from animals....uh, except those gorillas that learn it at the zoo. I guess it doesn't separate us from them. But things like badgers" *realises he's losing his point and the girl through his dorkiness, tries to regain his mystique سے طرف کی talking about wine*

Maybe there'll be some deeper explanation, like him having a deaf friend یا relative, but I can also totally imagine college Ted learning just to be pretentious about it :)