This is not a joke, Tom. Something has attacked our home and when that happens you don't just stand by; you fight it! Screw this creature that has come into our lives uninvited and is trying to destroy us! It will not defeat me.
Scruffles was the name given to a possum that invaded the Scavo family garden.
One day after coming home from a PET scan, Lynette noticed a hole in a flower bed in her garden. Her mother mentioned that she saw a possum the other day, so Lynette gets angry that nobody had told her. Lynette then makes it her mission to get rid of the possum. Lynette visited the garden center to collect a trap and poison. Parker asked her what's it's for, so she told him she's trying to get rid of it. Parker is upset that she might hurt "Scruffles", but Lynette says it's the only way to get rid of it.
When her plans to kill Scruffles failed, Lynette turned to Bree for help. She asked to borrow a gun as Scruffles ate around poison and the trap only managed to catch Penny. Bree explains that she cannot use a gun, but instead tells her to get an air rifle to scare away the creature.
On Halloween night, Lynette camped in the garden to shoot Scruffles with her gun. Concerned about his wife's obsession with getting rid of the animal, Tom tries to stop her and bring her inside. However, Lynette, feeling the possum is a metaphor for her cancer, tells him that she won't let Scruffles defeat her and she will fight for her survival. Tom then allows Lynette to do whatever she wants to feel safe.
Later that night, after Lynette found out she beat cancer, she walked outside to celebrate her freedom. However, when she saw Scruffles on the floor, dead, she felt guilty for it's death and apologized, as she'd beat cancer and she felt Scruffles was a metaphor for that.