Declining to Serve as Guardian?

When declining to serve as guardian of a friend's child, it is best to answer in terms of the increased family size of the restrictions placed by current housing.  Do not follow the example in an old Carol Burnett Show skit where a couple decided to act obnoxious and asocial with atrocious dinner manners so they would not be asked.  The other couple asked eventually because "you act just like we do."