OT but, a similar situation for me some years back.
I worked for a beer distributor as a sales rep. I had worked there for quite some time and was well liked by both owner and retail handlers of our products. One late evening after work on a Friday I had decided to stop by the VFW lounge for a cocktail or two. I got to the bar and decided to have a cold beer. The bar was packed. Rosie, the proprietor said hello to me and asked what I'd have. I said "Bud Light" please Rosie. She cracked a can open and set it in front of me. I grabbed the beer, tipped it back, and downed about half of it. As I set the can on the bar I noticed the owner of the company I worked for was also there. I nodded his way, lifted up my can to say "cheers" and took a drink. I looked at my boss with a smile and decided to give a cordial hello. I walked up to him and said "Hello Merlin, How are you?" He turned and said, "A lot better than you'll be doing come tomorrow." Confused at his comment I responded, "excuse me?" He said, "you're fired." I said "for what?" He stated sternly, "for drinking the competitors beer in public!...That's why!"
I had thought about what he'd just said for about two seconds when I asked, "Are you serious?" His reply, "You bet your a$$ I'm serious!"
I finished a few more beers and left. The next day I did the normal routine and went to work. Well, about 15 minutes of arriving I was approached by the owners son. He said, "Here Don" I asked...what's this? He responded ..your paycheck. You were fired.
Mind you, I was off work on my own time, out of company uniform that evening I was fired.