Tony winner Idina Menzel is gearing up to sing the phenomenal Frozen anthem "Let It Go" live on the Oscars on March 2. Watch as the If/Then star talks about why the song has millions of obsessed fans, including at a massive sing-along event on Good Morning America on February 26. (Watch that below, too!) Menzel even laughs that her four-year-old son, Walker Diggs, likes to belt out the unforgettable number in the bathtub. (We need a YouTube video of that stat!) As for her excitement and nerves about performing on the Academy Awards telecast, Menzel said, "This is a dream come true. I am just having fun with it." Catch the interview and the sing-along below.