Kobe Bryant was purple and gold as a 13-year-old -- signing his middle school friend's yearbook with "How bout those Lakers" -- and now the book can be yours.
Iconic Auctions has the super-unique piece of memorabilia on the auction block ... and it's pretty amazing.
In 1992, Kobe -- who just returned to the U.S. from Italy -- attended Bala Cynwyd Middle School in Pennsylvania ... where he played on the basketball team.
Bryant arrived midway through the school year, so he didn't have a standard school photo. He only appeared in the boys' basketball team photo.
When yearbooks were issued, Kobe's buddy asked him to sign the autograph page ... and what Mamba wrote was pretty prophetic.
"In a few years you probably will be dunking on me. Not!! How bout those Lakers. Your friend Kobe Bryant #24"
Kobe was just 13 years old in 1992 ... and wasn't a member of the Los Angeles Lakers (or the NBA) until June 1996.
Of course, Bryant -- even back then -- wore (and signed) one of the numbers, #24, that would eventually hang forever in the rafters of Staples Center.
Iconic tells us they expect the yearbook to sell for over $20k ... when the auction closes this weekend.