Du fleiper.

Fleiper is the present tense of the verb å fleipe, which means to joke, to kid, or to mess around.

So:

• å fleipe = to joke / to kid
• fleiper = joke / are joking / is joking, depending on the subject

In Du fleiper, it literally matches English You are joking.

Because Norwegian usually does not need an extra helping verb like English am / is / are with many present-tense verbs.

English says:

• You are joking

Norwegian says:

• Du fleiper

The verb fleiper already carries the present-tense meaning, so no separate are is needed.

Grammatically, Du fleiper. is a statement: You are joking.

But in real conversation, depending on tone of voice, it can absolutely function like English:

• You’re joking!
• No way, you’re kidding!

If you want to make the surprise even clearer in writing, people might use an exclamation mark:

• Du fleiper!

The infinitive is å fleipe.

A few useful forms are:

• å fleipe = to joke
• fleiper = joke / am joking / are joking / is joking
• fleipet = joked
• har fleipet = have/has joked

A simple learner-friendly approximation is:

• du ≈ doo
• flei- sounds a bit like English fly
• -per is roughly per, but with a Norwegian r

So Du fleiper is roughly doo FLY-per.

The exact pronunciation depends somewhat on dialect, but the important point is that ei in fleipe- is typically a diphthong, somewhat like the vowel sound in English my or fly.

Å fleipe is common, but it feels fairly informal/conversational. It is the kind of word you hear in everyday speech.

Depending on context, Norwegian also uses other verbs such as:

• å spøke = to joke
• å tulle = to fool around / be silly / kid around

So Du fleiper has a casual, natural spoken feel.

They are similar, but not always identical.

• Du fleiper often means You’re joking / You’re kidding
• Du tuller often means You’re fooling around / being silly / kidding
• Du spøker means You’re joking, but can sound a bit more neutral or standard in some contexts

In many everyday situations, they can overlap. A native speaker might choose one over another based on habit, region, or slight nuance.

In a normal main clause, Norwegian usually has subject + verb word order, just like English:

• Du fleiper = You’re joking

If you move something else to the front, then Norwegian often puts the verb before the subject:

• Nå fleiper du. = Now you’re joking.

That is a very common Norwegian pattern.

Yes, but then the word order changes.

• Du fleiper. = You’re joking.
• Fleiper du? = Are you joking?

That is a key pattern in Norwegian: yes/no questions often put the verb first.

It can do both.

Literally, it means that the other person is joking.

But very often it is used to react to surprising news, like English:

• You’re kidding.
• You must be joking.

So if someone says something shocking or hard to believe, Du fleiper! is a very natural reaction.