Why did Jesus ask for forgiveness?

If Jesus lived a perfect life, for what was he asking forgiveness when said the Lord's prayer? What "debt" or "trespass" had he committed that he felt needed to be forgiven? If he was just giving a model prayer that only applied to the fallible mortals listening, it seems that would mean he was being insincere in prayer, or that he was asking for something from the Father he didn't really need, which seems out-of-character for him.