Here is how one has to look at this. We have to keep very stringent on things such as this because once you open the door to allowing one then that usually ends up opening the door to more. I mean, where does it stop?
The next thing you know they'll be some cartoons anime or hentai involving underage human characters in their underwear and if the user who posts that got kicked they would then have an argument to be made using your standard.
Plus, I sort of agree with Leo17 when it comes to that image. To me, it seems very suspicious that out of all images you could ever find of SpongeBob you decide to use one that involved underwear. I am starting to suspect that you liked the attention whether it be positive or negative, and I believe you may be doing this purposeful to get that which you desire.