According to Jim Recap: The Importance of Being Jim
Jim brings home his new toy one day from work - a digital camera. The best thing is that it includes some pictures that the former owner forgot to erase. Cheryl doesn't even mind, because they are of the owner's new wife, and he dumped Dana to marry her. She asks Jim to make sure that he keeps the pictures so that Dana can see the pictures, and Jim agrees that he will keep them. Unfortunately, Jim and Andy get so caught up taking pictures in the back yard that they need more space - and those pictures get dumped.
When Cheryl brings Dana over to see them, Jim has to explain what happened, and instead of merely owning up to clearing out the space, he makes it worse by saying that he got rid of something that wasn't important to her, and then goes on to make it even worse by saying that everything is important to her, and if it was actually important, he would have kept them. Dana doesn't help, because she doesn't really care about the pictures, but the damage is done. So when Jim isn't looking, Cheryl takes the camera and hides it. She tells Jim that she threw it away.
Jim and Andy pretend that they don't care, but as soon as Cheryl and Dana leave the room, they get the kids and start searching the trash - unfortunately they can't find it anywhere, which means that Cheryl was just trying to get them going (which she did very well). So then Jim tries to get back at her by hiding her purse. She pretends to bite, then asks to make a phone call before they swap, and she calls her cell phone, which is in her purse, so Jim loses out again.
Finally, Jim dresses up the girls as himself and Cheryl in an attempt to "not lose the moment", but Cheryl knows what he is up to and won't bring out the camera. In a completely unscripted moment, however, Kyle decides to take his first steps - and then Cheryl does want the camera, so she pulls it out of her hiding place (which she doesn't reveal) and Jim eventually gets his camera back.
