I take my retro coffee mug with me whenever I fly, tucked in perfectly in the side slot of my laptop backpack. I usually ask for two Heneikens when I'm about 15 minutes out from boarding. One goes down the hatch and the second fills up my coffee mug - right there on the bar. Never had anyone say anything to me. That could just be from the confidence I exude when pouring, probably from the fact I didn't know it was against the rules until reading this.