Learn Hardcore Spanish (Spain): Mi amigo se pone nervioso cuando el wifi se corta. - My friend gets nervous when the Wi‑Fi cuts out.

Mi amigo se pone nervioso ≈ My friend gets/becomes nervous (there is a change of state).
If you said mi amigo está nervioso, you’d be describing his current state: My friend is nervous (right now), without focusing on the change.
Mi amigo pone nervioso on its own would mean my friend makes (other people) nervous – a different meaning.

So se pone is used because we are talking about him starting to feel nervous when the wifi cuts out, not just describing his state or saying he affects others.

What’s the difference between ser nervioso, estar nervioso, and ponerse nervioso?

They all relate to being nervous, but in different ways:

Ser nervioso: describes a general, inherent trait (what someone is usually like).
- Mi amigo es nervioso. → My friend is a nervous/anxious person (by nature).
Estar nervioso: describes a temporary state.
- Mi amigo está nervioso. → My friend is nervous (right now/at this moment).
Ponerse nervioso: describes the process of becoming nervous, usually triggered by something.
- Mi amigo se pone nervioso cuando el wifi se corta.
  → My friend gets nervous when the wifi cuts out. (He wasn’t nervous before; this situation makes him nervous.)

So: ser = character, estar = current state, ponerse = to become / to get.

Why is it nervioso and not nerviosa or nerviosos?

The adjective must agree in gender and number with the subject, which is mi amigo:

mi amigo → singular, masculine → nervioso
If it were mi amiga, you would say:
- Mi amiga se pone nerviosa cuando el wifi se corta.
If it were plural:
- Mis amigos se ponen nerviosos…
- Mis amigas se ponen nerviosas…

So nervioso is masculine singular to match mi amigo.

Why do we say el wifi? Is wifi masculine or feminine in Spanish?

In Spain, wifi is usually treated as masculine, so you say el wifi.

El wifi va mal. → The wifi is bad / not working well.
No hay wifi. → There is no wifi.

You may occasionally hear la wifi (treating it like la red, “the network”), but el wifi is far more common in Spain.

Using the article el also sounds more natural in this sentence than leaving it out.
Cuando el wifi se corta is more idiomatic than cuando wifi se corta.

What does se corta mean here? Why not just corta?

The verb is cortarse here, used pronominally, and it means “to cut out / to break off / to be interrupted” (by itself).

El wifi se corta. → The wifi cuts out / drops.
La llamada se cortó. → The call dropped / got cut off.

If you said el wifi corta, it would sound like the wifi cuts (something), as if wifi were actively cutting something else. With se corta, the idea is that the connection itself is interrupted, without specifying an agent. It’s like a passive/“it happens by itself” feeling.

Could I say cuando se corta el wifi instead of cuando el wifi se corta?

Yes. Both word orders are correct:

Cuando el wifi se corta, mi amigo se pone nervioso.
Cuando se corta el wifi, mi amigo se pone nervioso.

The meaning is the same. Spanish often allows both subject + verb and verb + subject, especially when the subject is something already known (like el wifi here). The order with se corta el wifi can sound slightly more natural in casual speech, but both are fine.

Why is the present tense (indicative) used after cuando and not the subjunctive se corte?

The choice between se corta and se corte depends on whether you’re talking about:

A general, habitual situation (factual):
→ use indicative
- Mi amigo se pone nervioso cuando el wifi se corta.
  = Whenever the wifi cuts out (it generally happens), he gets nervous.
A future or hypothetical situation that hasn’t happened yet:
→ often use subjunctive
- Mi amigo se pondrá nervioso cuando el wifi se corte.
  = My friend will get nervous when the wifi cuts out (in the future).

In your sentence, it’s a general recurring situation, so the present indicative: se corta is correct.

Is there any difference between se corta and something like se cae for the wifi?

Both can be used, but there’s a nuance:

El wifi se corta.
Focuses on the connection being interrupted / cut off (it stops working, comes and goes).
El wifi se cae.
Literally “the wifi falls”; it’s more colloquial and emphasizes the system dropping/crashing, similar to “the connection drops”.

In many everyday contexts in Spain, people say things like:

Se ha cortado el wifi.
Se ha caído el wifi.

Both are understandable, but cortarse sounds very natural for internet, phone calls, etc.

Could I use si instead of cuando, like Mi amigo se pone nervioso si el wifi se corta?

Yes, and the meaning is very close, but there’s a slight nuance:

Cuando el wifi se corta… → When(ever) the wifi cuts out…
Focus on the time/event; whenever that event happens, he gets nervous.
Si el wifi se corta… → If the wifi cuts out…
Sounds a bit more conditional or hypothetical: in the case that it cuts out.

For a regular, repeated situation, both cuando and si are possible. Cuando sounds more like “every time this happens,” while si emphasizes the condition.

Can I say Mi amigo se pone nervioso por el wifi instead? Does that mean the same?

Not exactly the same.

Mi amigo se pone nervioso cuando el wifi se corta.
→ He becomes nervous at the moment when the wifi cuts out (the event triggers it).
Mi amigo se pone nervioso por el wifi.
→ He gets nervous because of the wifi in general (maybe he worries about it; it’s a broader cause, not tied to a specific event of it cutting out).

The original sentence is more precise: it says what specific situation makes him nervous.

Are there other common verbs like ponerse used for changes of emotion or state?

Yes. Ponerse + adjective is very common for temporary emotional or physical changes:

ponerse triste – to get sad
ponerse contento – to get happy
ponerse rojo – to turn red / blush
ponerse enfermo – to get sick

Others you’ll see:

volverse
- adjective: often for more lasting changes of character
- Se volvió muy egoísta. → He became very selfish.
hacerse
- noun/adjective: often for gradual changes, professions, ideology
- Se hizo médico. → He became a doctor.
- Se hizo vegetariano. → He became vegetarian.

For sudden, temporary emotions like nervous, angry, sad, ponerse is usually the most natural:
Se pone nervioso, se pone triste, se pone furioso, etc.