S2·E12 Operation: K.I.S.S.

It is a clear case of Dr. Jekyll and Mr. Hyde when Numbuh 2's attempt to create a formula to strengthen hamsters causes him to transform into a teenager and back! Thrown out of the treehouse by his unknowing teamates, he seemingly finds solace when he runs into Numbuh 5's evil sister Cree, and she develops a crush on him!