Topsy got his revenge on the kids who threw white ground sparkles at him. The kids were off screen.
Petrie (tries some white ground sparkles and spits it out; the ground sparkles were yellow): Ewwwwww! Petrie no wanna throw white ground sparkles at Cera's dad no more; he got me good.
Cera laughs hard. Littlefoot sighs in annoyance while Spike says nothing.
Ducky: It is not funny, Cera!