The 23-year-old Scottish star has revealed he was left embarrassed when his debit card was rejected whilst buying shots for his celebrity pals after he made his debut on the Other Stage at the Somerset festival in June.
Speaking to the Daily Star newspaper's Wired column at the Q Awards at London's Roundhouse on Wednesday night (16.10.19), he admitted: "I"m really s*** at transferring money on to cards.
"I just played and I was so excited so I was like, 'Let's get some shots', and then I completed f***ed it.
"I think Jack Whitehall's sister's fiance paid as I f***ed it."
The 'Someone You Loved' hitmaker has become a breakout global superstar since he released his hit single earlier this year, but he still lives with his parents in Scotland because he doesn't earn as much as people think - while he splashes what he does have on grub.
He recently said: "There's always room to earn more. I still live with my parents so I don't think I am earning that much money!
"And all I spend my money on is food because I can't help stuffing my face. I am splurging on food and it shows, it's showing on my gut, my gut is expanding every day."
The 'Hold Me While You Wait' hitmaker admitted when he does get to enjoy some of his wealth, he has one purchase in mind.
He added: "I'd like to buy a nice watch one day but that's if I don't spend all my money on food...
"What do people with money buy? Exotic animals? Mike Tyson had a tiger, Justin Bieber had that monkey, Michael Jackson had a monkey too but none of these guys had big fat snakes."
