Animation stars Wallace and Gromit begin a nationwide tour on Bank Holiday Monday to hand out more than £100,000 to ill children.
Wrong trousers day takes place in June
They are also encouraging one million Britons to take part in Wrong Trousers Day on 29 June.
About 250,000 people have already signed up to pay £1 to wear sports-style trousers for the day in aid of children's hospices.
The tour begins at the Royal Hospital for Sick Children in Bristol.
It will then take in hospitals and hospices in Winchester, Nottingham, Birmingham, Sheffield, Manchester, Stockton, Newcastle, Edinburgh and Glasgow, presenting a £10,000 cheque at each.
The Wallace & Gromit Children's Foundation has also launched a competition to find people with the most ridiculous trousers.
Entrants should photograph themselves and post their pictures online, joining badly-dressed celebrities in an online vote for the "Wrongest Wrong Trousers".