About 200 people carrying rainbow flags descended on an east London supermarket for a mass "kissathon" after they received a complaint about a gay couple holding hands.
Thomas Rees, 32, and Joshua Bradwell, 25, were in Sainsbury's on Hackney Road when a guard told them a woman had complained about their behaviour.
The protestors danced outside the Hackney Road store on Saturday night before kissing in the aisles.
Sainsbury's apologised for the incident and offered the couple a £10 voucher.
Mr Rees said he had been holding Mr Bradwell's hand and may have put an arm around his partner's waist as they were buying food on Monday evening.
But after they paid, a security guard beckoned them outside to tell them about the complaint.
Mr Rees said it "knocked me for six" and left him "analysing how I'm perceived", but since the incident they had received messages of support from around the world.
Mr Bradwell said the number of people who turned out to support them was "absolutely insane".
During the event one person was heard to shout at the group to "get off my street", but the protesters carried on undeterred.
A spokesperson for Sainsbury's, which provided biscuits and water for the protesters, said: "It's been a really great event and an important opportunity for the community to show their support.
"We do our best to make sure everyone feels welcome in our stores but occasionally we make mistakes. We are working hard to make sure lessons are learnt."
The supermarket said it was conducting an investigation into the incident.
Two years ago, a "big kiss" protest was held at a Sainsbury's store in Brighton after a lesbian couple were asked to leave when one gave her partner a kiss on the cheek.