Video: Lady Gaga Performs with Kid Cudi

Lady Gaga kicked off her “Monster Ball” tour in Montreal, Canada, on Friday (Nov. 27). Gaga brought out opening act Kid Cudi to perform his “Poker Face”-sampled hit “Make Her Say.”

“Who is on my f***ing stage?!” she asked before introducing Cudi. “You listen to me, Kid Cudi. If you’re ever f***ing late to my show again, I’m gonna kick your ass.”