Play video games to make sure they're bug-free.
What does a Game Tester do?
A game tester plays video games before they are released to make sure everything works as it should. As a game tester, you are like a proofreader: Just as writers can’t pick up all their own typos, game programmers tend to gloss over errors because they are used to looking at the material.
It is your job as a game tester to play the game with attention to detail and find and document any glitches that exist. This involves everything from making sure you can complete the game, to seeing if the Death Scion of Doom interacts with the Artisan Light Beam Reflector in the manner that it should. In other words, you need to examine all details of the game, both big and small.
Because of the required attention to detail, game testing can become somewhat tedious. You need to make sure that every movement and option is functional, that each weapon, map, and skid of your tires looks and performs well. You will always run into a few (if not a lot) of malfunctions, and you need to report them when they pop up.
But in the bigger picture, yes, you are you are getting paid to sit and play video games. Granted you are not getting paid very much, but who really cares as long as you can make rent?