Incredibly, it wasn't the first time the humble hero had performed the move on a choking boy - a decade ago his son William got his dinner stuck down his throat and Dexter, 39, dislodged it.
"It was just a normal training," Dexter recalled last night of the May 31 practice session.
"We were setting up to do normal kick-off stuff and I kicked the ball off to [Dylan]. He's my fullback.
"He's normally quite good under the high ball but he just dropped it. A couple of the boys went rushing across to him and I said, 'are you all right?'"
The others yelled back Dylan was fine and training continued, but Dexter noticed something was wrong as Dylan began waving his arms around.
"When I got over to the boy I could hear him just wheezing. I asked what was going on and he could sort of pointed to his throat and I figured something was stuck in there," Dexter said. "I thought maybe his mouthguard had gone down."
Dexter performed the Heimlich manoeuvre - where sudden, strong pressure is applied to the abdomen - a couple of times, but the gobstopper was stuck fast.
Dylan kept gasping, squeezing what little air he could into his lungs and, crucially, staying conscious.
"I asked the kids to go down and ring for an ambulance and they scattered in 10 different directions. Just as I did that I tried [the Heimlich] another couple of times and out pops this gobstopper," Dexter said.
Dylan had "freaked out" and parents watching the training were worried he was dying in front of them, but after taking a few minutes to recover, Dylan was back into training.
Dexter, a senior Corrections officer at Waikeria Prison, said his regular first-aid training had come in handy.
Patrice Fynn reckons the whole team has been scared off scoffing gobstoppers, but Dylan had his reasons for sucking away at training. He'd just got to the good bit that takes a long time to reach and didn't want to spit it out.
She was worried Dylan might have suffered sore ribs because of the Heimlich but the teen soldiered on as normal.
The only sign of what happened was red eyes the next morning, from popped blood vessels.
She had texted Dexter but he had tried to play down his heroics - it was only through eyewitness accounts from other parents, who asked about Dylan afterwards, that she discovered how serious the situation was.
Dexter said gobstoppers were off the menu for rugby training now.
What should I do if someone's choking?
Mild choking: Encourage the person to cough. Ask them to spit the object out if they can.
Severe choking: Stand behind the person, slightly to one side. Support their chest with one hand and lean them forward so the object will come out their mouth. Give five sharp blows between the person's shoulder blades with the heel of your hand. Perform the Heimlich manoeuvre.
