How to Correctly Use Slang in Speaking and Writing.

How to Correctly Use Slang in Speaking and Writing

After more than twenty years of teaching English in Peru, I’ve learned something very important about slang: the problem is not using slang, the problem is using it without control.

Many of my students arrive at an intermediate or advanced level sounding grammatically strong but socially unsure. They ask questions like:

“Is this phrase too informal?”

“Do native speakers really say this?”

“Why does this sound strange when I use it?”

These are good questions. Slang is part of real English, and ignoring it completely can make your speech sound stiff or unnatural. However, using slang well requires judgement, cultural awareness, and restraint, skills that take time to develop.

This article is about how to use slang appropriately, not excessively, and not dangerously.

Why Slang Is Especially Tricky for Learners in Peru

One thing I’ve noticed over the years is that many Peruvian learners acquire slang from media, not from real-life interaction. Social networks, YouTube, movies, and music expose students to expressions that are:

Extremely informal

Region-specific (US, UK, Australian, etc.)

Age-specific

Sometimes outdated or offensive

Because learners don’t always see the social context, they may use slang in situations where it sounds unprofessional or inappropriate, job interviews, emails, exams, or with authority figures.

This is not a language problem. It’s a context problem.

1. Understand what slang is, and what it isn’t

Slang is not the same as informal English.

Informal English: acceptable in many social situations

Slang: highly casual, often cultural, sometimes temporary

For example:

Okay → informal but safe

Cool → informal, sometimes slang

Lit, dope, sick → strong slang, risky for learners

Before using a slang expression, ask:

“Would I use this with my teacher, my boss, or a stranger?”

If the answer is no, think twice.

2. Limit slang to speech, not writing

This is a rule I repeat constantly in my classes:

If it’s written, don’t use slang.

Slang almost never belongs in:

Emails

Essays

Reports

Exams

Academic or professional writing

Even native speakers avoid slang in writing unless they are texting close friends or writing creatively. For learners, written slang often looks careless rather than natural.

3. Use slang only in the right relationships

Slang is relational. It signals closeness.

Appropriate situations:

Speaking with friends

Casual conversations with peers

Informal social settings

Inappropriate situations:

Teachers and professors

Employers or clients

Job interviews

Formal meetings

In Peru, students are often taught to show respect through language. English works the same way, respect is expressed through formality, not friendliness alone.

4. Use very little, and repeat it correctly

One mistake I often hear is overuse. A student learns one slang word and uses it everywhere.

Native speakers don’t do this. They sprinkle slang lightly.

If you use slang:

Use one expression at a time

Use it exactly as you’ve heard it

Don’t combine slang expressions creatively

Slang is not flexible. Either it sounds natural, or it sounds wrong.

5. Be careful with humour and sarcasm

This is especially important for learners in Peru.

Sarcasm, irony, and joking slang are deeply cultural. What sounds funny in a movie may sound rude or confusing in real life.

Until you are very confident:

Avoid sarcastic slang

Avoid slang that involves insults, even joking ones

Avoid slang with strong emotional tone

When in doubt, stay neutral.

6. Ask before using new slang

One of the healthiest habits I’ve seen in advanced students is this simple question:

“Is this okay to say?”

Asking a teacher, native speaker, or trusted colleague before using slang publicly can save you embarrassment and misunderstandings.

Good English is not about sounding trendy. It’s about sounding appropriate.

7. Think international, not local

Many learners don’t realise that slang is often local, but English today is international.

An expression common in the US may sound strange in the UK or Australia. Slang that works in one city may not work in another.

If your English is for:

Work

Travel

Exams

International communication

Then neutral language will always be your safest choice.

In conclusion, slang is seasoning, not the main dish.

Used carefully, it can make your English sound more natural and relaxed. Used badly, it can damage your credibility very quickly.

After more than twenty years teaching English in Peru, my advice is simple:

Learn slang. Understand slang. But use it sparingly, and only when the situation truly allows it.

When in doubt, choose clarity, respect, and control. That is what real fluency looks like.