... Were trying to out-do each other. The boy said, "my dad is stronger than your dad"!  
The girl said "well my mom is a better cook then your mom"!
This went back and forth for quite some some before the little boy ran out of things to say until finally he pulls down his pants and says, "well, I have one of these and you don't"!  
The little girl thought for a moment, pulled her pants down and said, "well I have one of these! And with one of these, I can have as many of those as I want"!