Jesus often used stories & analogies to drive home a point, moral, or lesson. These stories often included unscrupulous characters that actually display some positive virtue or ethic that the listeners could learn from. These stories/analogies Jesus told are called parables.
After Jesus taught the disciples how to pray, He shared with them a story about the attitude with which we are to approach prayer to God. In this parable, Jesus teaches us that prayer is not about "niceness." We are praying to the Creator of the universe, so we are to "approach God’s throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need." (Hebrews 4:16). Jesus tells us to approach God with a "not-to-be-deterred" attitude or, as I like to call it, with Shameless Audacity! Pray continuously and pray expecting God to move...pray with faith & trust.