Local volunteers, radio personalities, firefighters and others will be handing out Big Macs and McCafe coffees Thursday for McHappy Day.
McDonald's spokesperson Darlene Black said this year all funds raised at restaurants in Sarnia and Petrolia will benefit Ronald McDonald House-SWO, London house.
She said when the house opened in 1985 it started with 12 bedrooms, and has since grown to 40.
"They're celebrating their 40th year so very exciting for them," said Black. "Obviously for us it holds dear for us here in Sarnia. Colleen Buckley our Owner/Operator used to serve on the board so it's a special place for us."
One out of every four Canadians have either stayed with RMHC or know someone who has.
"It's a place for families to go when their children are sick," said Black. "It's a five minute commute over to the hospital. It houses gaming rooms, a kitchen, all the amenities they'll need so that they don't have to worry about where they're going to eat and they can concentrate whatever is happening with their children."
Black said hungry guests can support families with sick and injured children by purchasing anything from their menu or a pair of McHappy Day socks on Thursday.
"There's so many order points now with the mobile app, drive-thru and the front counter," she said.
Since McHappy Day started in 1977, over $100 million has been raised for Ronald McDonald House Charities across the country and other local children's charities including Noelle's Gift, Big Brother Big Sisters Sarnia-Lambton, and Pathway's Health Centre for Children.
Last year, customers in Sarnia and Petrolia raised $38,563.40 for St. Clair Child and Youth.