The only thing that I could see about drinking at the airport would be specific municipal laws regarding alcohol in public. Im guessing you wont be stumbling down the terminal taking swings, so I BET nothing will happen, especially if you simply add it to a drink you buy.
On board, the usual FAA penalty for a noncertificate holder is a fine. They can range from a few hundred dollars to a few thousand.
Realistically, will you get fined if you get caught? I'm no expert, but I havent heard of anyone getting fined for simply bringing a drink on board (now drunkeness is a different story). I guess my advice would be to use your best judgement and see if you can feel out the FA
"A pilot's plane she is. She will love you if you deserve it, and try to kill you if you don't...She is the Mighty Q400"