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what's the big idea

what's the big idea

8.1
To ask why someone is doing something when you are annoyed or surprised
  • idiom
  • Informal
translation icon : cuál es la idea
  • He stormed into the room shouting, "What's the big idea?" when he saw the mess.

Examples

  • If you take her phone without asking, don't be surprised when she demands, "What's the big idea?"

  • Hey, what's the big idea behind this sudden change?

  • What's the big idea waking me up so early on a Sunday?

  • I was surprised when he asked, what's the big idea of moving the meeting?

  • What's the big idea waking me up so early on a Sunday?

  • He stormed into the room shouting, "What's the big idea?" when he saw the mess.

  • If you take her phone without asking, don't be surprised when she demands, "What's the big idea?"

Synonyms

what's with
vswhat's the big idea
  • Informal
262 7.9

Ask why something is happening or seems strange

expresses the same why question but with stronger surprise or irritation
what gives
vswhat's the big idea
  • Informal
15 8.9

Asking why something is happening when it seems wrong or surprising

asks why someone acts, usually with annoyance or surprise
what for
vswhat's the big idea
4 4.3

Used to ask why someone did something

asks the same reason but usually with annoyance or surprise
why in the world
vswhat's the big idea
1 8.1

Words people say to show strong surprise or shock

asks the reason for actions and adds annoyance rather than only surprise
what's the story with
vswhat's the big idea
  • Informal
1 8.2

To ask for information about a person or situation

focuses on asking why someone acts, often with surprise or annoyance

How Angry

what's the big idea
  • Informal
8.1
you're killing me
  • Informal
2 8.9

Surface Forms

Morphology

what's + the + big + idea

Literally the words ask ‘what important idea?’ so a learner could guess it relates to someone's reason or plan, but the conventionalized use is idiomatic—a challenging/annoyed demand for an explanation of someone's action. The pragmatic force (confrontation/annoyance) and routinized phrasing are not fully derivable from the parts, so comprehension is possible in context but not reliably predictable for a B1 learner.

Etymology

The question what's the big idea comes from asking about someone's big idea—as if you want to know their important plan or reason for doing something. One popular story says people began using it in an angry or surprised way to mean 'why are you doing that?'.