What does Psalm 3:2 mean?

This psalm was written by David as he fled from his son, Absalom. Absalom attempted to overthrow David and even considered sending 12,000 men to pursue and kill his father (2 Samuel 17:1–3). David avoided that fate only by the influence of his ally, Hushai (2 Samuel 17:15–16). Faced with those odds and the power of the enemy against him, it's not surprising that some would consider David's situation hopeless.

Shimei, most likely a descendant of former king Saul, was one of those who taunted David as he fled from Absalom. He threw stones at David and his servants and said, "Get out, get out, you man of blood, you worthless man! The LORD has avenged on you all the blood of the house of Saul, in whose place you have reigned, and the LORD has given the kingdom into the hand of your son Absalom. See, your evil is on you, for you are a man of blood" (2 Samuel 16:7–8).

However, David's flight from Absalom was not the first time he had been mocked. When he was a youth, David was the target of the taunts of the Philistine giant Goliath. As David drew near to fight Goliath, he endured Goliath's insults. Goliath cursed David by his pagan gods and said, "Come to me, and I will give your flesh to the birds of the air and to the beasts of the field" (1 Samuel 17:43–44).