A carrotmob - or 'reverse boycott' - is promoted as the opposite of a protest, with consumers encouraged to mob cafes which have adopted fair-trade practices.
It is based on the concept of encouraging positive behaviour with an enticing carrot/reward rather than having them being beaten into change, said Gleisner.
Cosset Cafe in Auckland's "sleepy" Mt Albert alone was awoken by a stream of supporters totalling nearly 500 people.
Owner Kellie Gray said she was stuck behind the coffee machine as the cafe was "swarmed" by fair-trade supporters who passed through.
"We were constantly making coffee and taking orders for the two hours. Lots of people passing through and lots of people hanging around and having a good time."
"A lot of people commented they were expecting a half hour wait for coffee and that didn't happen so I think we were pretty good," said Gray.
She said the message of fair-trade supporters was received loud and clear.
"They were there to stand up and say, 'Yup, we care about this'," Gray said.
Cosset Cafe donated 70 per cent of the day's earnings, which amounted to $1200 from coffee and food sales. But Gray said a lot of customers turned up intending to just donate money to the cause.
"There was a lot of social media and a lot of people picking it up on their blogs and passing it on which was really awesome that they cared about it," she Gray.
In Wellington, nearly 200 people mobbed Petone's Celcius Cafe.
"The second Carrotmob in Wellington was even better than the first! It was an amazing day, with lots of generous people enjoying great coffee in the sun," said Wellington's Carrotmob organiser, Melissa Keys.
New Zealand's first Carrotmob was held at capital city's Memphis Belle Coffee House last year.
Matt Morrison - on hand with a wheelbarrow full of free fair-trade bananas from his company All Good Bananas - shared tips on the trend.
"There is a growing movement of people that want to support fair-trade practices, and the turn-out today demonstrates that" he said.
Cosset Cafe's Kellie Gray said although the business made a loss in the two hours of hosting the Carrotmob, remaining income from the day was enough for them to break even.
"I care about the cause. We want to support fair-trade and coffee industry so it's all going in the right places," she said.
"Hopefully we'll be in the bidding again next year."