It's funny how those on the cusp of adulthood can be a little concerned about how they come off to others. And I say that because I've been there myself. I used to be terribly self-conscious about how people perceived me. That didn't stop until I went through a couple of painful personal episodes in my life that really knocked me for a loop and realigned my principles and priorities.
Me? I'm 30 years old with bills to pay, responsibilities to myself and the people I love. I've seen enough of the ugly side of life to realize that there's no harm in embracing your inner child - in fact, we might all be better off if we did just that. Without forgoing your grown-up responsibilities, you can enjoy a healthy dose of SpongeBob (or Rugrats, or Little Bear) and not think anything of it.