Shaquille O'Neal just came through in the clutch for one of his biggest fans ... making a special shoutout vid for his bar mitzvah -- and TMZ Sports has the vid!!
We're told 13-year-old Adam Huczneker had a Lakers-themed celebration over the weekend ... and the kid's uncle wanted to make it extra memorable, so he DMed the NBA legend asking for a quick message.
Not only did Shaq agree, he sent a video going all-out with every Jewish phrase he could think of -- even wishing the kid a Happy New Year.