Could this be bullying?

We have this teacher at our school who is literally everyone's favorite teacher. There is a wall in his room literally covered in drawings people make of him. Fanart if you will. I made a drawing of him as a mermaid (nothing bad at all, barely even looks like him), thought it was pretty good and funny, and posted it on Facebook. Lots of my friends thought it was funny or at least amusing. Skip forward a few days, a parent from our school emailed the drawing to my mom (who is also a teacher), and claimed that it was really mean to portray him as wearing "women's clothing" and that it was basically bullying. My mom got really mad at me and made me delete it, and said I could have been suspended. I really don't see it as offensive so what do you think?