For the special appearance, Baird wore a black sweatshirt with Eilish's face and "Billie's Mom" written on the front. Eilish sang her hit "Happier Than Ever." Later in the night, her brother ...

There was a moment midway through Monday night’s concert at Little Caesars Arena that summed up the Billie ... sweatshirt, a pair of baggy shorts and a camo-patterned cap thrust backward, Eilish ...