Happy Monday to all.
Today our idiom is how on earth.
We use this as a form of exclamation. For example when we want to show surprise, disgust, shock or even anger.
The "how" part of this idiom can also be replaced with the "Wh" words, such as When, Why, What, Where and Who.
How on earth did you eat all that food?
Why on earth are you going to Myanmar now? There is a civil war happening.