When I turned 21 (all so many years ago) I was given a "Beer In A Bag". Just add hot water. I don't recall if there was a yeast packet or not. Shake, store, serve. For what it was I remember it not being too bad. The first third was nicely carbonated and the rest just went down hill from there.
I must say that it gave me the start to home brewing. It just took me a few years to jump all in.