Template:Spoilerstart The episode begins with Mr. Small giving a boring lecture on the composition of happiness. The day comes to an end, and the students are dismissed. Banana Joe gives Darwin back his pen that he had borrowed. Gumball notices several bite marks on the pen and accuses Joe of biting the pen, who denies this. Unconvinced, Gumball swears to "exact justice" over the trivial act.

At lunchtime, Gumball goes up to Joe, and tells him that anything can be solved with a simple apology. Rather than apologizing for chewing the pen, he instead forgives Gumball for his accusations earlier. Gumball is agitated, and asks if he can borrow his tube of glue.