Margo wants to leave flowers for Karin, who told her of Jase's infidelity.
They race to Karin's house, and Quentin observes that when he floors the gas in the minivan "it whimpered" (1.5.4). The same thing happens to Quentin.
After leaving flowers, they drive to Jase's house to leave him a fish and a note.
His house has an alarm system, so they rush in, alarms blaring, and Margo throws the fish through a window (a closed window, breaking it) then spray-paints an M on the side of the house before running away.
Next stop is Lacey Pemberton, who made the mistake of minding her own business and not telling Margo Roth Spiegelman about Jase.
Margo squishes the fish under Lacey's backseat and orders Quentin to spray paint the roof of her car.
He holds up his blue finger and Margo holds up her own blue finger, and like a pair of ETs, they touch.