Red cards are being handed out to shoppers this week as part of shopworkers' union Usdaw's Respect for Shopworkers Day.
The campaign focuses on verbal abuse suffered by staff. It is hoped the red cards, which will carry campaign details, will spread the message that anyone abusing staff can be prosecuted.
Usdaw general secretary John Hannett said: "Our research has found that at least half a million shopworkers are verbally abused every working day, so our members are saying enough is enough."