What happens next?

How to store liquor in stainless steel flasks
Fill your flask with hard liquor.
Flasks are intended for use with straight, undiluted spirits. In general, it is best to fill a stainless steel flask with hard liquors, such as scotch, whiskey, rum, or vodka.
Avoid adding mixers to your alcohol, since many of these contain corrosive or perishable ingredients that can damage your flask. Avoid putting corrosive or easily spoiled liquors in your flask.