While Tommy and the gang were in the jungle looking for Nigel Thornberry, Chuckie gets lost from the rest of the gang. As Chuckie got lost, he tumbles down a hill and lands into a mud puddle. While washing his clothes at a lagoon, he runs into Donnie Thornberry, who steals his clothes and makes him end up with his shorts.
As Chuckie tried to find Tommy and the rest of the gang as he was in Donnie's shorts, he protects a baby monkey from a bunch of bigger ones. The baby monkey then gives Chuckie the fruit he was carrying which causes Chuckie to believe he must be a wild boy now.
Later on, after Donnie saves Tommy and the rest of the gang (who have mistaken Donnie for Chuckie since he was wearing his clothes) from Siri the Clouded Leopard, Chuckie finds him and asks him to give him his clothes back, which he does. After Donnie gives Chuckie his clothes back, Siri shows up right in front of him, but Donnie manages to grab him and put him in Dil's stroller and push him away to safety. During the chase scene, Chuckie reunites with Tommy and the rest of the gang.