One humorous birthday quote is from Bob Hope: "You know you're getting old when the candles cost more than the cake." Funny birthday quotes are available on WishesQuotes.com and BrainyQuote.com. Each site contains both humorous and more serious-natured quotes.
A Mitch Hedberg quote from BrainyQuote.com reads: "I wanted to buy a candle holder, but the store didn't have one. So I got a cake." BrainyQuote's site provides quotes from a number of well know celebrities. WishQuotes.com provides categorized quotes and expressions including creative ways to say happy birthday, a top 10 quote list and birthday wishes for a best friend. It does not provide quotes attributed to people, as all quotes are anonymous.