The idiom "big deal" is used to express a lack of enthusiasm or excitement about something that is supposed to be important or impressive. It is often used sarcastically to show that the speaker does not think that the thing being discussed is as significant or impressive as others might believe.
For example, if someone says, "I got an A on my test," and another person responds with "big deal," they are essentially saying that getting an A is not a big deal and not worth celebrating.
The phrase can also be used to express annoyance or frustration when someone is making a big deal out of something that is not important. For instance, if someone is complaining about a small mistake in a report, another person might say "it's not a big deal" to suggest that the mistake is minor and not worth getting upset about.
Overall, "big deal" is a casual and informal expression that is used to downplay the significance of something or to express annoyance at someone who is making a fuss over something trivial.
• "Winning the championship was a big deal for the team, they worked hard all season."
• "The politician's scandal was a big deal and caused outrage among the public."
• "As a Nobel Prize winner, he knew that his research was a big deal and could change the world."
• "I ate breakfast today, big deal!"
• "Getting a promotion at work is a big deal for most people."
• "So what if he's a millionaire, it's not a big deal to me."