In this cartoon, the three magi present their gifts, but when the third magi announces his gift's symbolism (regarding the death and sacrifice of Jesus), the Holy Family looks at him in horror. Jesus is still very young at this point, and I've been informed that it is considered uncouth to bring up the eventual death of people when they've only JUST BEEN BORN. Anyway, the third magi complains that he "drew the short straw," implying that the three magi bought their three gifts together, then drew straws to see which of them would get to give the more or less desirable gifts. It is in this way that he came to be burdened with myrrh and its implications.