>> reporter: when she's not playing mommy -- ♪ happy birthday to you ♪ >> reporter: she's center stage, performing all 18 number one singles night after night. >> this is my quick change room. the quick change room. just sent this in from paris. we have all different designer. he sent this beautiful dress in. no reveal. >> reporter: you can't see that. only people in the show like mariah and myself know the set list. don't try to ruin our show. >> thank you. i'm coming to your show. i'm screaming. mariah! i'm michael strahan in las vegas. >> i feel like he's going to make a cameo in her show. >> i wouldn't be a surprised. >> he makes a cameo in everybody's show. he'll be here next week.