Contrary to the actual words used, a cry baby neither cries nor is an infant, but is a fully grown adult who whines too much and should know better.

A cry baby will normally complain about the most petty things, like there being no packets of brown sugar on their hotel room tea tray, the fact the train is four minutes late, and being dumped by their significant other.

The only acceptable way to deal with a cry baby is to pretend to physically cry when they start complaining, by rubbing ones eyes and quivering ones bottom lip in a totally OTT manner, followed by the put-down "don't cry about it".

A person who gets easily upset if they don't get thier own way.

a person who whines cries and throws a fit over silly bullshit. Someone who whines just to whine and argues just to argue. A silly bitch.

Someone who whines and cries.

A fan of Melanie Martinez. (Like me!!!!)
Someone who obsesses over Melanie Martinez. (Also like me!!)

It is also a movie from 1990 that stars actor Johnny Depp as a character named Wade "Cry-baby" Walker. It is a spoof of the decade of the 50's, and cheesy musicals.