Oh, is that a cactus?
Actually, in school we had a student teacher for like two weeks in one of my classes and my friend and I kept calling each other cacti as a joke (I don't remember why).
The student teacher came over because we were being noisy and I told the teacher how my friend was calling me a cactus and it was hurting my feelings, so she told my friend seriously "Please don't call him a cactus" and then walked away.