According to Jim Recap: Wonder Woman
When Cheryl goes to the mall and nearly gets mugged, she does what any sane woman should probably not do - she runs the guy down and tackles him to get her purse back. If you lived with Jim, you probably would do the same. But when she and Dana get back in the car, they have to sit a while before either one of them can get it under control enough to drive home, and she doesn't even want to tell Jim.
It turns out that when Jim finds out, he does exactly what she didn't want him doing - he goes completely overboard and starts following her around. He even jumps on a guy running after Cheryl through the parking lot (the guy was bringing Cheryl her credit card because she forgot it).
Then he rents a couple of German Shepherds to protect the house when he's not there. The only problem is that they don't speak English (being German), so you need to give them commands in German. And while not exactly vicious, Gunther and Fritz do take their jobs seriously - so when Jim and Cheryl forget the commands upstairs, they find themselves locked in the bathroom.
Luckily, Jim manages to slip them some cough syrup, which probably isn't the best idea, but it does get them out of the bathroom. And Jim promises that he'll take it easy from then on.
