In my classroom, there's a plethora of Batman things. I won't apologize for them. I think it's important for my students to know that teachers are actual real people with interests.
Which is why I think it's adorable that my students had this good luck card made for them last year during standardized testing:
Yup. Even the third graders know what type of things are acceptable in my classroom, TMNT pictures being one of them!