I think it's supposed to be don't pee on me and tell me it's raining, i.e. Don't expect me to believe your lies.
Close enough for me.
"Don't hurt me and then pretend like you had nothing to do with it.
You argued, privately, to each member of the committee that I should be fired and now you come by on my last day to tell me how sorry you are about what "happened." Don't piss on my leg and tell me it's raining."
Must be an R. Kelly song.