How do you make a sentence using understatement?

"It's a bit chilly outside" would be an understatement if it were, say, 10 degrees below zero.

Here are some more examples:

* "I'm slightly disappointed" when you're actually devastated.

* "That was a little bit of a challenge" when you faced a near-death experience.

* "The traffic was a bit heavy" when you were stuck in a standstill for hours.

The key to understatement is using language that minimizes the true extent of the situation, often for humorous or ironic effect.