His coach, Craig Budd, said many people had joined the quest to find boots for Shaq, but it seemed nobody in New Zealand made them that big.
"Everyone from the Bay of Plenty Rugby Union to referees - everyone, we've all been trying to track some down for him," Mr Budd said.
"He's a great kid. He trains really hard and puts in the effort. All the boys are really supportive of him."
Shaq started playing only this year, but he's already caught a few professionals' eyes, mostly because of his size.
"They said they can teach him the skills and that sort of thing, but they're pretty impressed with him," Mr Budd said.
Shaq doesn't know yet if he'll want to take rugby further after he finishes Year 13 at the end of the year.
"Maybe if I get a little better," the teenager said. At the moment, he just enjoys playing.
Shaq doesn't know exactly how tall he stands, but he thinks it's well over two metres. (All Black lock Brodie Retallick is a mere 2.04m.)
Said Shaq: "I just tell people I can't fit under doorways."
Being so tall has disadvantages: "I can't go to Rainbow's End because I'm too big for all of their rides."
But one of the bonuses is that at concerts, he can always see the stage over everyone's heads.
Mum Adele Kameta said her mother now took care of Shaq's shoe problem as it had become an expensive and difficult task.
"I gave up a long time ago trying to find him shoes," she said.
Grandma Lynn Kameta, 63, said she often made trips to Auckland, Whakatane and Rotorua in search of shoes for her eldest grandson.
"He's just been blessed with awful feet," she laughed.
On one occasion, she got a call from someone saying they had seen two pairs of size 20 shoes in a Rotorua shop.
"I got there and I just snapped them up. They told me they were about to send them back because they had been sitting there for so long."
Lynn Kameta said she had spent thousands on shoes for Shaq.
"I just tend not to think too much about it. But I've spent a lot of time hunting around for shoes for him."
Told about All Black squad member Luke Romano's similar problem, with his size 17 feet, she laughed: "Oh he's got little feet!"
Mrs Kameta said finding shoes for her grandson became particularly difficult when he was 13 and had size 16 feet.
"I feel so sorry for him when we go to a shoe shop and all he can do is look.
"A pair of shoes to him is like gold. He keeps the boxes and he has them all lined up in his closet."
His size aside, Shaq isn't like most 18-year-olds - to celebrate his recent landmark birthday he stayed at home and played on his Xbox because going out drinking "isn't really me".
But he said if someone was able to find some size-18 rugby boots for him, that'd be good.
CAN YOU HELP
If you have some boots for Shaq, call Kawerau College (07) 323-8143.
Additional reporting: Vaimoana Tapaleao