After Phil confronts Mike about having shaved off half his face, Phil initiates a prank war to get back at Mike. Phil first tries to fill Mike's sleeping bag with poison oak, but is hit with blue ink that Mike rigged in a fake Christmas present box left for Phil. The ink doesn't come off, so Phil is forced to cover it up with makeup. The next morning out that Mike moved into a new house down the street and isn't sleeping in the sleeping bag anyway, so the poison oak did nothing to him.
Mike refuses to tell Phil where he lives, so Phil follows him that night and attempts to sneak into Mike's house and put the poison oak in his bed, but Mike catches him. After forcing Phil to rub the poison oak on his own balls to prove it isn't poison oak, Mike reveals that he knows it is poison oak and knows what Phil was planning to do. He vows to get back at Phil.
The next morning, Phil wakes up on the edge of a cliff by the beach and falls off, landing on an inflatable mattress, courtesy of a prank by Mike. Phil looks up to see Mike giving him the finger (only the fourth finger) from the top of the finger and throws sand at him angrily. Mike tells Phil that he'll get him back for throwing sand at him and Phil panics, knowing he's outmanned in this prank war.
Phil hides from Mike and begs Todd for help. Todd tells Phil he doesn't have time to help him because he's too busy having two girlfriends. Finally, Todd says enough is enough and agrees to help Phil. Todd and Phil confront Mike, Todd having shaved half of himself like Phil. Mike apologizes to Todd for him becoming involved and says the prank war is over. Phil doesn't believe that it's truly over.
Phil sets up a security system of bubble wrap around his bed that night, to alert him if Mike is near. Carol tries to talk him down, showing him family photos of Mike and Phil as children. She encourages Phil to show the photos to Mike to resolve their conflict. Instead, Phil pranks Mike by faking a letter (covered in poison oak) from their parents written to Mike while he was in space.
Meanwhile, Todd struggles with juggling all of his responsibilities with two girlfriends, having difficulty maintaining the balance between Gail and Melissa. At first, he tries to be honest to both of them, but ends up alienating both women by talking about the other to each of them. Todd has a breakthrough after realizing he has to be there for Phil during his prank war. He gives an impassioned speech to all of the women assuring them that he can give 100% of himself to everyone (including supporting Carol with her infertility woes), impressing all of them.
Phil goes to apologize to Mike for faking the letter from their mother. He gives Mike all of the real letters from their parents. Mike confesses that he misses their parents and Phil agrees that he does as well. On his way out, a bucket of flour falls on Phil. Mike apologizes, saying he didn't know they'd make up right then.
Carol approaches Todd and asks him to put Tandy's baby inside of her. Todd agrees without hesitation.