Operation: H.O.M.E. Codename: Kids Next Door : Season 5 Episode 21

It starts out when Numbuh 3 was a baby, she receiving a purple rainbow monkey called "My First Rainbow Monkey" at birth. The next couple of scenes show Numbuh 3 taking her first steps, learning to ride a bike, and graduating into the Kids Next Door with My First Rainbow Monkey by her side each time. My First Rainbow Monkey also grows a beard throughout these flashbacks.