Sarah Palin on Jeremy Lin -- I'm Going LINSANE!!!!!!!!!!!!!!

Call her Sarah Pa-LIN ... because the former Presidential candidate is the new Knicks' sensation's biggest fan -- even showing off her brand new "LINSANITY" t-shirt on the streets of New York today.

According to Sarah, Jeremy Lin is everything America stands for -- calling him "an American story ... uplifting, positive ... he unifies our country!"

But when it came to deciding between Lin and Tim Tebow -- Sarah reverts to politician mode, telling us she can't decide between the two ... she loves them both. Lame.

So we gotta ask ...