When he worked undercover in the Noah’s Ark Circus case, Ciel Phantomhive posed as a servant who wished to join the circus. His test involved balancing on the high wire, which Ciel could not have passed if not for Sebastian’s “help”. Ciel was later given the stage name “Smile”, possible because Joker wanted to encourage him to smile more.
I remember trying my best to stifle my laughter when I was reading the manga at home, but my family thought I was going crazy anyway! Thanks to Paladin for sending this in!