Portal 2 was awesome. Actually, it still IS awesome. So go buy it if you haven't. It's puzzles plus clever humor, not that toilet humor that promulgated in most modern games! Speaking of bad taste, here's a pin up I made of the main character, Chell, along with her companion cube.
Yes, she's got booty shorts. Yes her head is ginormous. But is there really a problem with that? No. There isn't.
But seriously, if you haven't done the portal thing, it's short(ish) and rewarding.
Otherwise you'll miss out on all the internet memes, like "The cake is a lie." and a bunch of stuff about lemons and Cave Johnson. You'll see.