Can you put a mimosa in a Starbucks cup, and drink your own booze on board your flight? I’ve been on a flight where the woman sitting next to me had a coffee cup with wine from the American Airlines Admirals Club. A flight attendant realized it and confronted the passenger.
Things escalated quickly. We were in first class, and the woman was offered both a predeparture beverage and could have free wine once we were at cruising altitude. But she wanted her wine for taxi and takeoff, too!