At Nickelback's Nashville concert on Tuesday night (Sept. 14), frontman Chad Kroeger was singing Joe Nichols' praises, saying, "He's a good-lookin' son of a bitch, isn't he?" and calling "Tequila Makes Her Clothes Fall Off" one of his favorite (expletive) country tunes. He even sang a little bit of it. But as Kroeger performed the band's smash hit, "Rockstar," Nichols himself sauntered out on stage halfway through and sat down next to Kroeger to sing it with him. Nichols took the verse about how he's gonna be great like Elvis, hire bodyguards and get a front door key to the Playboy mansion. It's one of those thrilling concert moments you kind of have to see to believe, and thanks to Joe Nichols' tweet about it, you can.