The Real Decoys - S4.E10

Sandra gets a job as a meter maid. When Pearl gets her purse snatched while on her way to the bank with Mary and Rose's dues, Sandra and Mary hatch up an idea to stage a stake-out in the park. Rose and Mary pose as elderly women.

They become suspicious when a skater continues to skate past them and suspect that he is the mugger. An older man comes and sits on the bench with Mary and Rose. He eventually snatches their purses and the skater, who is an undercover cop tries to handcuff him. Sandra decides to be the hero when she jumps in, but she handcuffs the skater instead and the mugger gets away.

When they get home, Pearl realizes that the dues money wasn't in her purse but pinned inside another bra.