Another student named the plan "Fight McMillan".
Another wrote: "Last year apparently the cops were called and we were nearly not gonna get the venue this year."
The organiser then asked everyone to "chill" because "the head students" had arranged a meeting at lunchtime yesterdaywith McMillan and another teacher.
A student posted: "I'll bring a banner." Another asked: "Should we protest outside the meeting?"
The organiser declined to speak to the Herald, saying via Facebook Messenger: "We're just having a few laughs and it's all a joke, that's literally all it is haha. We deleted that group chat by the way, thanks!"
McMillan said the first he knew about the protest was at the lunchtime meeting.
He did not order the students to close the protest page but said the plan to bus students to the ball in August would go ahead.
"It's about keeping our kids safe and making it more accessible," he said.
Costs had prevented some students from attending past balls organised by the decile 1 school, which was placed under a commissioner last year and was in the news last week when a 16-year-old boy was rushed to hospital after being bullied at the school. One student was suspended and another stood down afterwards.
Last year the Manurewa community helped students attend the ball by donating dresses, suits, shoes and even jewellery.
Some teachers did nails and makeup, and Manukau Institute of Technology hairdressing students provided free hairdressing.
McMillan said the turnout of about 200 students and their partners represented about 80 per cent of Year 12 and 13 students, but the cost of transport to Alexandra Park still kept some away and he wanted to remove that barrier.
"As we do after every ball, we review it. We are looking at what other schools in Auckland do with their balls, and one of the things other schools have found is that providing a bus from school makes it easier for students to get there and it's not a barrier to students participating, so we are just trying to remove that barrier," he said.
He said several schools held their balls at Alexandra Park on the same night last year, causing traffic congestion. To avoid this, he plans a red-carpet welcome for students when they arrive at school with their partners to catch the bus.
"By having everyone arrive at the school first, they can come in on the red carpet, they can have the first non-alcoholic drinks at the school, so we can do it in a way that allows the families to get photos, we can bring all the kids together, and everyone knows they are getting there safely," he said.
He said "a couple of our students" told him at the meeting yesterday that they had "stuffed up" by starting the protest but had shut down the group when it "got out of hand".
"That's fine," he said. "It's one of the great things about being young and passionate for kids, they engage with stuff. I did say, 'I wish you'd come and talked to me first'."