When spoken to children, this phrase communicates a gentle reminder to speak clearly and enunciate. When spoken to adults, this phrase communicates both insult and an urgent desire to be kicked or punched squarely in the nose without any hesitation.

For this reason, careful consideration should always be made about the approximate age of the person speaking, not only out of respect but in avoidance of severe pain, injury, and bloodshed assuming none is wanted.

What you say when a person stutters, or won't tell you something. Demeaning, because it equates them to a small child. Better if use with a "you can do it!" for mock encouragement.

What a single mother shouts at their son/daughter after backhanding them.

A person demanding verbal communication from someone who is not speaking.