Presumably, they’re the person who everyone is singing happy birthday to, and hosting during that specific moment in American Idol is standing there awkwardly and unsure what to do with yourself.
Although we’re not entirely sure what Ryan Seacrest meant with that analogy, Bobby Bones is apparently picking up what the American Idol host is putting down.
It’s an oddly specific way to describe the judges giving notes, but it’s apparently apt according to Bones.