Can a graduate student take undergraduate classes?

Next semester I will be going to graduate school and working towards my MBA. However, I am interested in the Japanese language (taken 2 semesters of it Junior year but couldn't senior year due to needing to graduate). Even though it is not part of the MBA requirement whatsoever, and most Japanese language classes I assume are undergraduate (at least the level that I am at), am I allowed to take those undergraduate classes even though it won't count towards my graduate credit. I figured I want to learn the language sometime in the future so might as well utilize the university's resources and just pay out of my pocket for the class.