My Dad bought me my first drink for my Deb after party when I was 16. The "after party" was just a few girls at a friend's place and was supervised by her parents. I remember being in the bottle shop with Dad and having to choose something for him to buy me. I went with a four-pack of pre-mixed malibu concoctions in little white bottles.
I remember feeling giddy and giggly after the first couple of sips (I'm sure I must have imagined it!). Only drank half of one bottle for the whole night!