A Cowes local received the ultimate birthday surprise after discovering a $5 Instant Scratch-Its ticket sent by their sibling was worth $100,000.

The ticket, purchased at the Cowes Newsagency, had been sitting in the winner's mailbox for about a week before it was opened.

"I'm not sure if it's quite sunk in yet. I'm still a bit numb," the winner said.

"It was quite funny. When I scratched it, I realised I had a win and thought, 'Yay, I've probably won $5 or $10'. Then I scratched the prize amount and I was gobsmacked.

"I thought it had to be some sort of fake ticket. I'm really glad it wasn't.

"My sister gifted me a few different Instant Scratch-Its tickets for my birthday. She sent them via mail and they were sitting in my mailbox for probably a week before I got to them.

"I'm not sure how she feels. I told her and I think she was even more shocked than me."

The winner hasn't made any firm plans for the prize yet but said a new phone and a celebratory dinner might be on the cards.

Cowes Newsagency owner Angela Banik said the win had created a real buzz among staff and customers.

"We were thrilled to hear the news. Our whole team is so excited," Angela said.

"Our customers have already congratulated us on the win. It creates talk about how people would spend the money and how great it is to hear of a win at our outlet.

"This is our second big prize and it gives us goosebumps to think about how this will change a person's life.

"Congratulations to our winner. We hope it brings joy and happiness to you."