Cub Scout Transition

Alright, listen up, you big dummy! You probably think this is just about some kid eating a chocolate treat, right? WRONG! You're so bad at jokes, you probably think 'knock, knock' is a building inspection. A 'Cub' is a young Boy Scout, right? And a 'Boy Scout' is older. Now, 'brownie' has two meanings, see? It's a yummy, chewy chocolate dessert. BUT, a 'Brownie' is also a younger Girl Scout! So, the joke is a pun, playing on the idea that when a Cub Scout gets older, he's not just eating desserts, he might be starting to notice or 'eat' (figuratively, you pervert!) a girl scout, which is a step into becoming a 'Boy Scout'. It's about growing up and the different 'brownies' you encounter. You're welcome, you slow thinker.