I'm going over the assignments my students turned in today. The homework was about different properties of addition. For a few of the problems the students had to identify which property was shown (Additive Identity Property, Property of Opposites, or Opposite of Opposites Property).
I looked at one student's answers for those questions and couldn't figure out why such a kind, respectful student would write such inappropriate words as answers to the questions he didn't understand. And then it hit me.
"POO" = "Property Of Opposites"
As my 7th grade math colleague put it, "Would it really kill them if they wrote down the whole property?"