A 40th birthday marks the end of youth and the onset of maturity. Everyone feels differently about turning 40: Some embrace it as a new life passage, while others mourn the passing of youth. Etiquette rules depend largely on how someone feels about this milestone birthday; in general, however, avoid potentially humiliating gag gifts and cards.

The recipient may not appreciate gag cards about middle-age and gifts such as novelty dentures, diapers or walking aids — particularly if she is sensitive about getting older. Gag gifts and cards are generally frowned upon, particularly if you are not on intimate terms with the person celebrating this milestone birthday. They may be acceptable, however, if you know someone well and he doesn’t mind a little teasing about his advancing years. If you plan to host your own 40th birthday party and don’t mind novelty joke gifts, specify this fact on the invitation.

Some people may want to celebrate their 40th birthday quietly and with little fuss. Don’t throw a surprise party for a spouse or family member unless you’re sure she will appreciate it. Ask her how she would like to celebrate her birthday a few weeks beforehand. Throw a huge surprise party if she makes it clear she wants to celebrate in style. Respect her wishes if she wants to spend her 40th birthday in a restaurant with just a few family members and close friends.

Giving gifts at adult birthday parties is not mandatory — even on milestone birthdays. You can, however, bring a gift if you wish. If in doubt over what to bring, flowers, chocolates or a bottle of wine are always appreciated. If you plan to host the party and don’t want people to feel compelled to bring gifts, state this fact on the invitations.

Avoid birthday toasts that might make the birthday celebrant feel humiliated, including references to 40 being over the hill, bath chairs or rapidly advancing death. You can still use a little humor when toasting a friend's, spouse’s or family member’s 40th birthday, however. Try Jack Benny’s “Age is strictly a case of mind over matter. If you don't mind, it doesn't matter.” If you are asked to make a speech, a little self-deprecation will break the ice. Think of Lucille Ball’s timeless maxim: “The secret of staying young is to live honestly, eat slowly and lie about your age.”