DeMarcus Cousins Goes Off On Security Guard For Trying To Bar Autograph Seeker

DeMarcus Cousins unloaded on a security guard who was trying to block a fan from getting an autograph from the NBA star ... and the unique scene was all captured on video.

While Cousins and the Milwaukee Bucks took on the Rockets in Houston earlier this month ... Boogie spotted one of his biggest fans in the crowd and dapped him up.

The two then posed for a pic ... and when the fan -- noted YouTuber JiDion -- asked for an autograph on his #15 Cousins jersey, Boogie was all about it.

But, a security guard stepped in and tried to shut the whole thing down ... which clearly ticked off Cousins.

"I can sign his jersey! Stop acting like that," Cousins told the arena staffer. "You taking your job too serious!"

The security guard fired back, "Excuse me?!"

But, Boogie kept his head down, signed the jersey and then left the area to get back with his team.

JiDion, meanwhile, was fired up over it all -- you can see in pics and in the video he was absolutely giddy over the interaction.