When did your toddler totally go off of sippy cups?

well i dont have a child but i have a step sister who is about 4 that lives with me and she was off them by atleast 4. and of course she cried and complained that she wanted her sippy but we told her "big girls dont drink from sippies" and at first we took cups and out straws in them to get the feel of a sippy but then eventually took the straws away and let her drink strait out of the cup.