My two-year-old does this. However, we tell her that if she is going to cry because she is not getting what she wants or thinks she is not getting what she wants, then she can stand there and cry. Sometimes, she just gets upset because she says, "I want," or, "Give me," or other demands and we don't tolerate that. (She knows please and thank you.) We also tell her that when she calms down and uses big girl words (she's very articulate and has an expansive vocabulary), we will talk. She still may not get it, but she is learning to ask properly and to discuss.
For the most part, I think she knows that we will not give in, but she still tries.
Nip this in the bud now. My MIL raised my husband's little sister to get what she wants when she wants it. Even now, at 24, she knows that if Mommy says no, she just has to throw a fit. (Then she wonders why she has few friends, can't really get dates, let alone a boyfriend.... Yes, she does still live at home and doesn't really have a real job, just paid into an MLM that is going nowhere. She also has two cats to whom she refers herself as "Mommy". She tried referring my daughter and her cats as cousins, and me as their aunt, but I nipped that quickly.)
Anyway, start now before it gets worse.
