Dictionary
num'ber two'
1. someone or something that is second in rank, order, or importance.
2. defecation: used esp. by or with reference to children.
3. make, do, or go number two, Informal.to defecate: used esp. by or with reference to children.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.