^^^Hmmm, I'd always taken the phrase to be full-proof, even tho foolproof actually makes more sense.
It is the original sense, but 'full-proof' obviously works, too, albeit in a slightly different way. On the forum, it would naturally the preferred variation considering its faint evocation of alcoholic content.
It is the original sense, but 'full-proof' obviously works, too, albeit in a slightly different way. On the forum, it would naturally the preferred variation considering its faint evocation of alcoholic content.