Inspired by US hit show Man v Food, Les got his chops around a monster 2ft hot dog loaded with added extras.
By completing the Pix Axe Challenge, dreamt up by owner of Pappy's Traditional Smokehoose in Wishaw, North Lanarkshire, Les secured years worth of free monthly family meals for children who are being treated in Yorkhill Children's Hospital in Glasgow.
Les, an MBE for his fundraising work, completed the challenge in under 20 minutes.
He said afterwards: "I will never eat another hot dog again."
The Pick Axe challenge, created by Jordan Clements, is a 2ft baguette with four hot dogs, topped with beef brisket, pulled pork, chilli, cheese, onion rings and macaroni cheese and potato wedges on the side.
Les added: "I was a bit daunted by the size of the plate of food, which was actually very tasty, but I knew I had to power on and get through it. I don't feel so good now, though.
"I would like to say a massive thanks to Jordan for his generosity. When children are seriously ill, it affects the whole family so I know that a meal out together is a very welcome treat."
Pappy's opened five weeks ago in Wishaw's Main Street and specialises in Man v Food eat-offs, including the Chilli Ghost Wing challenge, made with eye-watering chillies which are among the hottest in the world.
Jordan added: "I have known Les supported his work for a long time.
"We were always planning to donate the meals, even if Les didn't finish the challenge, but we didn't let him know that."