The Bible uses the phrase "The Day of the Lord" about 26 times in 13 different books. Nine of the 16 old testament prophets mentioned it. Peter and Paul spoke about it in the New Testament. Jesus used parables to speak of the judgment day.
Matthew 24:50 The lord of that servant shall come in a day when he looks not for him, and in an hour that he is not aware of,
Luke 2:11 For unto you is born this day in the city of David a Savior, who is Christ the Lord.
Luke 12:46 The lord of that servant will come in a day when he looks not for him, and at an hour when he is not aware, and will cut him in pieces, and will appoint him his portion with the unbelievers.
I think these passages point out the reality that all days belong to God, and that there will be a final day of reckoning where we will account for the use of our days. Robert Brault has a humorous blog about the topic, which I have pasted in below, about Judgment Day.
1. Be on time.
2. Tell the Lord you've heard a lot about heaven and like what you hear.
3. Be neat, alert, make direct eye contact.
4. Don't stare at the beard.
5. When the Lord speaks, lean forward, look interested.
6. Be familiar with the Lord's background. ("I really liked your Ten Commandments.")
7. Be clear on where you want to be in five years.
8. Be honest about personal flaws. ("I tend to be too forgiving.")
9. Do not hesitate to underscore qualifications. ("I go to church every Easter.")
10. Make it clear that you'll accept the standard benefits package.
~~ Robert Brault