A fellow was very much in love with a beautiful girl.  One day she told him that the next day was her birthday.  He told her he would send her a  bouquet of roses, one for each year of her life.

That evening he called the local florist and ordered twenty-one roses with instructions that they be delivered first thing in the morning.

As the florist was preparing the order, he decided that since the young man was such a good customer, he would put an extra dozen roses in the bouquet.

The fellow never did find out what made the girl so angry with him.