You don't sound like a dumbass when you don't know what calibre you were shot with... you sound like a liar.
Let me break it down for you anyway.
9mm is a pistol round. However, there are pistols chambered in rifle calibres and vice versa. There are a number of reasons for this - every round has unique penetration, expansion, and fragmentation characteristics that makes it better or worse for a given application. A friend of mine bought a Ruger PC-9, a 9mm rifle, so that he could practice his rifle marksmanship at an indoor pistol range because he lives in an urban area where there are no large outdoor ranges. You can't fire a typical rifle in a typical indoor range, because rifle rounds tend to penetrate much farther than pistol rounds and would go right through a backstop that's not designed for them. That's obviously going to be a problem in a city.
.22LR is a tiny round. Here's a picture to give you an idea...
"Left to right are: 22, 25, 32, 380, 9mm, 357 SIG, 38, 357, 40, 45, & .223."
..and for further perspective, here's a guy holding a .22LR round:
There are both pistols and rifles chambered in .22LR. This round can be used for "varminting," or hunting very small game such as squirrels. There are also .22 competitions. But the only real advantage to .22LR is that it's cheap. It can be fired on any range. Thus it makes a good practice round for getting your marksmanship fundamentals down on the cheap. It's not good for killing anything bigger than a rabbit. Keep in mind that the brass isn't going anywhere - the business end of any of the above rounds is only the copper-jacketed part.
