On the brain

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7 September 2026

On the brain

We use this expression to say that someone is obsessed with something or always thinks about something. It's often negative.

Written: No

Spoken: Yes

Formal: No

Informal: Yes

Example 1

I get so bored talking to Nigel. All he's interested in is football.

I know. He's got football on the brain.

Example 2

Are you coming to the party on Friday? Donna will be there. Donna's great.

Will you shut up about Donna! You've got her on the brain!

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