When Melissa refuses to put out in the backseat of Alan's car and demands he gets his own place if they're going to continue seeing each other, Alan, actually decides to pick up a second job.  He actually begins working for his mother as her assistant and helps her show homes.  Soon Alan discovers one of the properties is vacant and lies to Melissa about renting it and invites her over for wine and well, medically induced sex.  However, when Evelyn walks in on them with a client, the two of them take off in their underwear and Alan ends up dumped and possibly as a registered sex offender.

Meanwhile, Chelsea is getting fed up when Jake shows her no respect at home.  Charlie tries to step in to get Jake to respect her or he's getting kicked out.  When that doesn't work, Chelsea and Jake end up going out and bonding and decide that it's Charlie that's driving a wedge between them.  Of course.  Poor Charlie went from ultimate bachelor to completely whipped.

The episode's title, "Laxative Tester, Horse Inseminator," comes from a suggestion given by Charlie to Alan for new jobs for him to consider.