Why did Pi’s brother say, “What’s this I hear about you having a new name . . . I didn’t realise you liked the colour yellow so much?”

Pi's brother is referring to the names he is usually teased with....

"I didn't realize you liked the colour yellow so much."
The colour yellow? I looked around. No one must hear what he was about to say, especially not one of his lackeys. "Ravi, what do you mean?" I whispered.
"It's all right with me, brother. Anything's better than 'Pissing'. Even 'Lemon Pie'."