Spanish Error

I was at the Red Hills International Horse Trials yesterday and they had those cool portable sinks by the portapotties. There was a sign on it that said:
"Not for drinking or cooking"
No para beber o cocinar."
I almost wish I had a sharpie (could have been the first to tag this portapotty I used...I couldn't believe that I was using a plop-John without any any any writing in it) so I could have crossed out the "o" and changed it to a "ni."

That's all I got.