Steve-O went to great lengths to pull off a seemingly harmless protest against SeaWorld using a freeway sign ... and now the California Highway Patrol is recommending he face charges for it.
The CHP says its investigation found the "Jackass" star should be charged with vandalism and trespassing. As TMZ first reported ... Steve climbed a freeway sign that said "SeaWorld Drive" and changed it to read "SeaWorld Sucks."
By the time cops arrived, Steve and his five-man crew were long gone ... but police eventually saw the video Steve-O uploaded to YouTube. Now, it's in the San Diego D.A.'s hands.
Steve-O tells TMZ, "I'd like to thank the CHP for breathing new life into this story. Bring on the publicity because SeaWorld sucks. R.I.P. Joan Rivers."