"Do you have any piss?"

Yes, this is what one of my 4th grade students asked me today. I looked back at her horrified, and said, "no, no I don't have any." She said, "no piss?" again, and I replied, "No, no, I don't have any piss." She then said "I have 16 piss" and motioned like a fish with her hands. You can imagine the look on my face when I realized she was asking me if I have any fish!