Many places in the Bible record the second arrival of Jesus like a thief. Among them, revelation 16, section 15 clearly shows that Jesus' second coming is as unprepared as a thief, reminding us to always be vigilant and be a good servant waiting for Jesus' second coming:
Rev 16: 15 (Look, I'm coming like a thief. Blessed is he who guards his clothes so that he will not walk naked and be seen to be ashamed! )