Actually ,it WAS made for adults it originally aired on Adult-Swim but when the producers realized they had a very wide youth audience Nickelodeon got it, hence the wide fan base, merchandise and it airing on Nickelodeon.
Was Spongebob Originally For Adults?
Yes, it was supposed to be for adults (on Adult-Swim) but when the people who made Spongebob noticed that kids were watching it more than adults they made it on Nick
Yes, spongebob is made for adults.
No it was made for kids..but it has some generic things that seem inappropriate but that's just so the adults would enjoy it because sometimes adults are stuck watching cartoons for children....teens may turn things so that it seems inappropriate but it has always been a show for children