It’s 11th’s catchphrase, just like Uncle Jiu’s fantasitic and Xiao Shi’s allow-y.

Every time he called out Geronimo, it was because he didn't know what would happen next. Although he didn't know what would happen, he decided to enjoy the process of falling and rising first.

He enjoys falling as much as he enjoys flying.

These two completely opposite experiences may be the same thing for him.