Just kidding means “I'm only joking”: you say it to show that what you've just said wasn't serious. Kid here isn't “a child” but a verb meaning “to tease, to joke”. In texts it's shortened to jk. A close relative is You're kidding!, a reaction to surprising news, like “No way!” or “Really?”: the other person doesn't think you're joking; they're just surprised. The phrase is informal and doesn't belong in a message to a teacher or colleague.
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statement + just kidding; I'm just kidding; You're kidding (me)!; I'm not kidding
- I've eaten all the pizza. Just kidding, there's half left in the fridge.
- You're moving to Canada next month? You're kidding!
- I'm not kidding: the exam has been moved to tomorrow morning.
What changed
First versionDon't be angry, I joke!
RevisionDon't be angry, I'm just kidding!
I joke in the present simple describes a habit, as in “I like making jokes in general”. For a joke you made a moment ago, you need I'm joking or the informal I'm just kidding.
Just kidding cancels the joke you've just made, while pull someone's leg describes the action itself, teasing someone: Relax, I'm only pulling your leg. I'm not kidding works the other way round: “I'm serious, no joke.”
Your turn
My brother said he had sold my bike, then laughed: "Relax, I'm ___ kidding. Your bike is still in the garage."
Show the answer
just — The brother admits it was a joke: the bike is still there, so it's I'm just kidding. I'm not kidding would mean “I'm serious”, that the bike really was sold, which contradicts the second half of the sentence.
Write a short exchange: you play a joke on a friend and then admit it. Show what you said as a joke and what's really true.
Me: I left your birthday cake at the shop. Tom: What?! Me: Just kidding, it's hidden in the fridge.
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