fun run 
noun informal
An uncompetitive run, especially for sponsored runners in support of a charity.In addition to being a fine eatery, Sorrentino's has installed itself in the community hosting charity events, sponsoring fun runs and giving everyone a great excuse to get garlic breath....
- The National Autistic Society has entry forms for several of the UK's top marathons and fun runs and is inviting runners to raise much-needed funds through sponsorship.
- Corporations whose products are blamed for encouraging obesity and causing heart disease are only too keen to improve their image by sponsoring life-enhancing fun runs and marathons.