Despite the verbal abuse, he said good luck messages had come from Tokoroa to Northland.
"She [his grandmother] sends me a lot of text messages that all her friends from her local bowls club are right behind me, so that gives you a very heart-warming boost of confidence."
Mrs Cooper, who will support the Wallabies on Sunday, still lives at the tidy Kaikohe home where Quade spent much of his childhood.
Pictures of the whanau are everywhere, but pride of place in Mrs Cooper's living room - above even her and her late husband's international bowling medals - is an action photo of her grandson in the yellow jersey, about to offload. On the opposite wall is a photo of Quade and teammates with the Queen, taken a few years ago at Buckingham Palace.
Of her famous grandson, she said: "He's a good boy. I suppose all grandmothers say that." On who she thought would win the second semifinal, she said: "May the best team win. If the Wallabies don't win, it's not the end of the world. It's just another game.
"I just want people bad-mouthing him to leave him alone ... that's all out of jealousy to him."
Kaikohe Bowling Club president Dion Davis said the bowlers supported Mrs Cooper and her grandson but would remain loyal to the ABs.
"We have known Millie and her husband Nesbit for many years and we would like to think we're supporting her, but this week it's a bit tough," he said.
"As close as we are to her and Quade, when it comes to the All Blacks and Wallabies game, we can't switch loyalty," Mr Davis said.
A great aunt of Cooper, who lives in Kaikohe, can't pick out a clear winner for the epic clash but is likely to tilt towards the ABs.
"He's a nice boy, not arrogant," she said.