Play video content EXCLUSIVE TMZ.com

Shia LaBeouf displayed raging patriotism over the weekend at Mount Rushmore.

Shia's fellow tourists tell us, they thought they he was just a random crazy until they got close ... then realized the guy without the shirt was the famous actor, screaming "AMERICA!!!!!!"

An old lady eventually asked LaBeouf to tone it down ... and things got weirder. We're told LaBeouf claimed he was a Marine and then asked her on a date.