Rudy Giuliani is FURIOUS at the Houston Texans for staying in their locker room for the national anthem before Thursday's game ... saying, "Maybe they should stay in the locker room forever."
"Maybe that's where they belong."
The former NYC mayor was at the 9/11 Memorial on the 19th anniversary of 9/11 when we asked him about the drama before the NFL season opener ... and Rudy didn't hold back.
"I think [the Houston Texans] should kiss the ground of the stadium that they're in America.