The Birthday Deck is the ultimate trick for strolling or close-up magic when you would like to give away a special memento to a person having a birthday.
You ask the person having a birthday if they received the birthday card you sent them. When they say no you bring out a deck of bicycle cards casually showing them front and back asking them to choose their own "birthday card." You write a little birthday message on the card and place it in their hand. You remind them that they could have chosen ANY birthday card, again showing both front and backs of the rest of the deck, but they chose the card in their hand. They turn it over and now has a real birthday card printed on the back.
For the finale they blow on the rest of the deck like they are blowing out candles and all the other cards turn blank.