On Dec. 2, Britney Spears' fiancé Sam Asghari gave the singer a glittery and floral "B"-shaped cake with a white chocolate heart that says "Happy Birthday Britney" to celebrate her 40th birthday.

No matter how old you are, having a happy birthday is one of life's great pleasures, says Tamar Hurwitz-Fleming, author of How to Have a Happy Birthday.Click here to download this cake-shaped zine ...