Find the best paper to wrap presents for someone turning 21! Celebrate this milestone birthday with the extra thought of wrapping the gifts in unique paper meant to honor the day. In some countries 21 is seen to be the age that one becomes an adult. In the United States the 21st birthday is a significant milestone -- it is the point at which a person may legally purchase alcohol, tobacco, and, in some states, marijuana. 21st birthday celebrations may include drinking alcohol and, of course, the sharing of gifts!