Steve-O Duct-Tapes Himself to Hollywood Billboard to Promote Project

Steve-O's up to his old tricks, and though his latest stunt isn't his gnarliest ... it's pretty damn funny.

The 'Jackass' star attached himself to a Hollywood billboard Thursday morning with the help of a bunch of black tape, in what he believed was a super safe publicity stunt rigged by professionals.

As you can see ... Steve-O was covered from his chest to his knees in the duct tape, leaving his arms free to take a selfie for social media -- after all, the whole point of this was to promote his new special.

We got him while he was plastered up there, and he told us he was wearing a diaper underneath. He also confessed he wasn't sure his stunt was legal ... but said he rented the billboard, and just wanted to make people laugh.

The prankster claimed there was zero chance he'd fall while pumping up his upcoming special ... it's called "Gnarly," btw, and we have no doubt the title fits.

Steve-O hoped to not use up any city resources getting him down, but despite his wishes ... the L.A. Fire Dept. showed up rather quickly to get him down safely.