Its not really necessary. Sippy cups was invented to make weaning off bottle easier and start drinking normally with a cup or straw. If your child refuses you can try some other steps to get him to get use to sippy cups. Examples: Dip the spout into breast milk or formula before giving it to your baby. ... Switch halfway through a feeding. ... Modify the sippy spout. ... Work in reverse order. ... Offer your baby a straw. ... Try other beverages. ... Show your baby how it's done.