Patient Observation Chart Prank

I admit it, I put a harmless prank note in a patient's observation chart once. It said something like, 'Patient requests extra chocolate milk.' I wanted to lighten the mood because I was having a rough day and saw my coworker doing the same thing with another patient's chart. But I've been second-guessing myself ever since. Is it unprofessional? Was the patient confused or annoyed by it? Why did I feel better after doing something silly like that?