Ariana Grande goes off script to sing deep cuts for her mom’s birthday

“It’s actually a very special day: Today is my mom’s birthday,” the pony-tailed pop megastar said of her mother, Joan (who, for the record, turned 51 on Tuesday). “I haven’t done these songs in a couple years but ... they’re mom’s favorites. ... She’s like, ‘Why don’t you do those songs?’ Check it out!