This is one of Joey's lame jokes. Ross is sad about the divorce, but Joey's personality is a playboy. He thinks Ross's divorce is definitely a good thing, but he doesn't understand why Ross takes marriage so seriously, so I think his joke means that only children will attach great importance to what they have (marriage), and adults should not. Because he thinks that he can meet more girls and have more choices after divorce, he is asked to pick up a spoon and eat ice cream with different flavors.