This is happening because the event name has a : in it. In order to resolve this you will need to remove or replace the : with a different character.

To edit the name:
  1. Navigate to Communities>Special Events>Friends Asking Friends>Kintera Thon
  2. Hover over the event name and select Website Info
  3. Click Event Information
  4. Remove the : from the event name
  5. Click Save
  6. Navigate back to the Webinfo Checklist and click Publish This Event Now

Note: Once you make the change, it should take affect quickly for new shares. Existing shares will not change. Further, it is possible for the change to be delayed sometime. If Facebook does not reload the site information but uses its own cache, it won't change until Facebook recrawls the site. We do not have a way to force this.