public static bool operator ==(MyShape lhs, object rhs)
{
   if( object.ReferenceEqual(lhs, rhs) ) return true;
   if( object.ReferenceEqual(lhs,null) || object.ReferenceEqual(rhs,null) ) return false;
   ...
}
public static bool operator !=(MyShape lhs, object rhs)
{
   return !(lhs == rhs);
}