He bets on major European league games, and with the World Cup coming to a climax, he is closely following the matches in South Africa. For the 18-year-old, the tournament held once every four years is a slim chance to make a fortune.
However, his football betting balance sheet over the years, he says, has been mostly in the red. 'I think the win-loss ratio is one to three or four. Overall, I'm losing money.'
Although he has never borrowed money to place bets or cover his losses, Ah Kei admits he sometimes feels he would be better off saving that money. On average, he bets once a week on major European league matches. His bets range from HK$100 to HK$500 per match.
'I could have bought models or video games with that money. With football betting, I could lose everything, and I often do,' he says.
Ah Kei, now a Form Five student at a night school, has been betting on football since Form Two. He placed his first bet when he accidently clicked on a pop-up advertisement link to a football betting website.
'I thought it was no big deal. Later on, I became more immersed - it's easy and convenient,' he says.
Like many others, Ah Kei might have become addicted to gambling without knowing it.
'I don't think gambling has any control over my life. It's just a hobby to me. I believe I can quit if I really want to,' he says.
A study released last month showed that 10 per cent of young people aged between 11 and 24 have gambled online. This was a jump from 2 per cent in a similar survey conducted in 2003.
The recent study was conducted by Chinese University's sociology department. Ninety-five per cent of troubled youths and 28 per cent of ordinary students were found to have gambled one way or another.
The researchers interviewed 703 troubled youths - who were identified by 12 social service agencies as 'at risk' - and 4,734 secondary students between February 2008 and January this year.
Ken Chan Kam-ming, a social worker at the Hong Kong Council of Social Service, says there has been an increase in the number of calls for help from young gamblers since the World Cup started.
'One of them said he lost HK$200,000 in three matches in a row,' Chan says. Some were in debt after borrowing money to cover their losses.
'Once, there was a Form Four student who placed his bet on an illegal website. He initially bet HK$100 on a match, but raised his bets when he was losing. In one year's time, he accumulated a debt of more than HK$100,000,' Chan says.
'Debt collectors poured red paint on the door of his flat and threatened him. In the end, his parents had to pay them off.'
He says these teenagers did not see gambling as a problem. 'They're having money problems, and they see betting as a way out. This thinking puts them in a vicious cycle of losing and owing more money.'