What is that one show in Cartoon Network were these kids went in the computer?

Answer 1

I believe you are referring to the series Hack, I'm not sure which series of Hack though. It's about these kids who play a Virtual Reality game called "The world" and have to play through it before they can get back out and into the real world.

Answer 2

If your talking about adventure time when Finn the human and his talking magical dog Jake went inside a video game. There is also johnny test where he, Susan and mary his psycho genius twin sisters and his talking dog dukey went inside a tinymon game so they can capture tinymon. The last one is level up where 3 gamers and a friend play a game like world if warcraft and by mistake bring the game into the real world and they try to stop them by beating every single one of the monsters that they know are from the game. I know this because I watch these shows everyday with my brother.