According to Jim Recap: All the Rage
Jim gets into a shouting match in the yard with the neighbors - that's right, all the neighbors. It's so bad, he even loses his shirt and drops his pants in the process. All because of The Thumper, a guy who drives down the street with his music so loud that everyone can hear it. It seems like Jim may finally be going off the deep end. When The Thumper finally comes by for a second pass, Jim jumps in the car with Andy to get him... and promptly backs into a police cruiser. When the neighbors get a load of this, the clothes come off again, and this gets Jim and Andy a date with the anger management course.
To make matters worse, Dana hits up Cheryl with a quiz from a magazine, trying to convince her that Jim has IMS - Irritable Male Syndrome. Jim, of course, will hear nothing of it, and wants even less to do with it when he gets to the anger management group and has to hear about other people's feelings. At least, he doesn't want anything to do with it until he hears about one guy who got a placard so he can park in the handicapped spot because of his medical condition. Then he's all ears.
When he gets home, Jim announces to everyone who will listen that he's got the IMS, and he's got it bad. He brings in his medical information and it's an excuse for just about everything. Where he thought that Cheryl was milking him in Good Grief, he's going to flip it around here, and he's going to use it for everything it's worth. Even better is Cheryl's on his side! She announces to everyone that he has the IMS, and finally she has an excuse for all the stupid stuff that he does.
But all good things must come to an end, and eventually he tells her the truth - he doesn't have a condition. At least, unless he has had it since he was six, because that's about how long he's been a jerk. And with that, the IMS is gone and Cheryl's back to her regular old jerk of a husband and she has to tell everyone that she's just married to regular old Jim. There are no excuses for that.
