Guardians' Josh Naylor Headbutts Tito Francona In Epic Walk-Off HR Celebration

When it comes to celebrations, Josh Naylor is unmatched ... 'cause for the second time this season, he lost his mind after a walk-off HR -- this time headbutting his own manager!!!

Naylor -- who previously went bananas after hitting a game-winning dinger back in May -- stepped to the plate in the bottom of the 10th inning with the Guardians trailing 6-5 on Wednesday night ... and then went oppo off Twins pitcher Jharel Cotton to win the game for Cleveland.

As he was rounding the bases, he got rid of his helmet -- which his manager, Terry Francona, appeared to pick up and put on -- and then he went crazy with his teammates.

But after Josh was mobbed by his team at home plate, he found the helmeted Francona -- and then slammed his forehead right into Tito's!

The clip is hilarious ... at one point following the blow, Naylor can be heard shouting, "Give me that sh*t."

Of course, back in May against the White Sox, the 25-year-old slugger made history when he drove in 8 runs in his final 3 at-bats -- and then became unhinged.

Josh proclaimed he wanted "all the smoke" repeatedly, and went insane in the dugout.