Dangit, it's making me hungry!
Anyway, TF2 is having one of its periodic free weekends right now, lasting until Sunday at 1 PM PST/4 PM EST. If you're at all interested in the game, you can try it out for free -- just install Steam and start the download. This was what got me into the game when before I would have sworn blind that I had zero interest in any online shooter.
For new players, I do have a few suggestions. First, there are nine classes whose play styles are wildly different, and some of them are much harder to get a hang of than others (I'm thinking Spy, Engineer, and Demoman, especially.) I would recommend you start out by playing Pyro, Medic, or Sniper.
Pyro is not hard to get into: get up close to someone (ideally from behind) and set them on fire, then laugh at them as they run around screaming. Also if you didn't burn them to death run away because they'll try to kill you. Your flamethrower has a secondary attack, which is an airburst that shoves people away. This is also extremely funny, especially if they were on the edge of a high cliff at the time.
Medic is the sort of class where a skilled one can turn a match around almost singlehandedly, but even a newbie Medic is useful because everybody likes healing. Switch to Weapon #2, the Medigun. Look around for somebody on your team yelling "Medic!" (a little cross symbol in a word balloon will appear above them so you can track them down.) Shoot them with the Medigun, holding down the attack button, and they'll recover health. You can buff people up to above their maximum health, too. Healing people increases your Ubercharge meter; when it's full, you can use your secondary attack on a teammate and both of you will become invulnerable for ten seconds. Obviously this can be really handy in pushing through a strong enemy defense. Plus, as you trail along after other players you can see what the different classes are capable of, which is handy for when you decide to play them.
Finally, as a Sniper you hang back and use the secondary attack on your rifle to bring up the scope. Then try to shoot people in the head from across the map. The longer you stay zoomed in, the more damage you do, and a headshot is always fatal. Try to hit slow-moving enemies like Heavies or anyone dumb enough to stand still. Watch out for Spies and Pyros and pretty much everyone converging on your location because you'll make enemies fast if you're any good.
Note that if you're getting frustrated with a class, you can and should switch any time you want to. As mentioned, the playstyles are all quite different. On a related note, there are many different servers and don't feel obligated to stay on one if the one you've connected to is full of weird or annoying people.
My second suggestion is to look for a server that's running one of the in-house Valve maps (2Fort, Dust Bowl, Granary, Gold Rush, Gravel Pit, and Well are the biggies) and doesn't have a whole bunch of rule changes. I've played a lot of custom maps lately and doing so just reinforces how much better at this Valve is than anyone else; there are many subtle elements that make the difference between a map that "feels" fair and balanced, and a map that "feels" frustrating and unfair. I'd even stay away from "honorary" maps like Fastlane or Steel that have been picked from the community by Valve. Man, Fastlane. All those stupid dead ends and random tunnels and boring graphic design and long approaches that are no good for close combat classes. I hate that map so much... Sorry, digression. You'll also find that people are generally more polite and friendly on servers that run standard maps, for some reason.
Finally, don't play Arena mode without knowing what to expect. Arena is much more like traditional Counter-Strike and such, where you can't respawn during a match, and so much more careful play is required.
So yeah. TF2! Worth a shot, right?
It tastes great.