I haven't done it in years, but wouldn't be averse to going that route again, especially on longer flights.

Back when I was young and didn't know better, a flight attendant caught me and admonished me. She didn't keep me from doing drinking (I only had 1-2 airplane bottles), but explained the rules in no uncertain terms. So I understand the reason for being clandestine. The Listerine bottle is an interesting idea, though I'm more of a brown liquor guy, so that could be a problem. Though I guess there's the "old school" Listerine.