Dennis joins up with an environmentalist group, but his altruistic intentions quickly sour when he's snubbed by the activists. Dee and Mac decide to raise a baby they find in the dumpster, but quickly find out that it's not nearly as fun as they thought it would be, and Frank and Charlie take the concept of recycling a bit too far.

Dee gets involved with a famous local rapper who might be mentally challenged, and whose success inspires the rest of the gang to start a band.

After Mac arrives to the bar with scratches on his neck and exhibiting strange behavior, Frank comes to the conclusion that he is the serial killer terrorizing young women in Philadelphia. Frank sets out with his trusty chainsaw and a doubtful Charlie to find evidence to implicate Mac in the murders. In search of another suspect, Dennis and Dee do a little role-playing in order to help themselves better understand who they might be dealing with.

When Dennis is mistaken for a recently released child molester, he is more bothered by the fact that the guy is overweight rather than him being a sex offender. Meanwhile, Mac tries once again to bond with his ex-con father, who shows an interest in Dee.

Mac and Dee become vigilantes in order to remove the homeless from their neighborhood, while Frank and Dennis impersonate police officers.