Why did Chris call part of his life "being stupid"?

As said by Chris, what was the second part of his life called?"I call this part _______."

A、

Riding the Bus

 'Internship'

'Running'

'Being Stupid'

Why did Mark call to his mom?

Why did his master call him "Darkie"?

A、

Because it was a good name.

Because he was a bad horse.

Because he was black.

无

Why did the call from his old acquaintance change his life?