Flex in slang means to show off, displaying things or achievements in a way that usually annoys other people. People use it about social media posts and conversations among friends. In neutral speech and IELTS Speaking, say show off, and in writing, boast about.
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flex + noun; flex on + person; a flex (noun)
- He keeps posting his new car online just to flex.
- Buying the most expensive phone isn't a personality, it's a flex.
- She wasn't flexing, she just genuinely loves talking about her research.
What changed
First versionHe always tries to flex to his coworkers about his salary.
RevisionHe always tries to flex on his coworkers about his salary.
You show off in front of someone, and in slang that's flex on someone: on shows the showing-off is aimed at other people. To might seem logical by analogy with show something to someone, but it doesn't combine with flex.
Besides the verb, there's the noun a flex — the thing someone is showing off: Getting three job offers in one week is a real flex. If someone is simply sharing news without trying to impress anyone, that's not a flex.
Your turn
He keeps posting expensive gifts just to flex ___ his followers.
Show the answer
on — The fixed expression is flex on someone, so it needs the preposition on. To doesn't go with this verb, even though it might seem logical.
Describe a time when someone (not necessarily you) was clearly flexing — showing off a thing or an achievement. Say exactly what it was.
My cousin keeps flexing his new sneakers on everyone in our group chat.
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