What is the worst thing parents can do to their parents?

When I asked my parents about this question, they said that the worst thing parents can do to their parents is "disobedience". Disobedience to parents may cause arguments. We should avoid this kind of attitude. Being obedient is one of the best things that parents to their son/s of daughter/s. We should also obey our parents because they know what's best for us. :)

                                                                                                      -Raymund Sarmiento