Languages are like fire. It's a primitive psycho technology that enable collective thoughts. Like fire once it spreads there's no undoing it.

The language one uses determines the mental models made available to the users. A collective's soft power is embedded in its language. Watch Arrival (2016) for a glimpse of the extreme.

Manglish/Singlish have this unique features of appending 'lah's as postfixes to sentences. Side note: Chinglish interestingly (used by Chinese outside Malaysia) do not incorporate 'lah's.

What most people here don't see is that English is mostly as a medium to deliver their own mother tongue. A typical Malay person speaking English is really speaking Malay using English. As do other ethnic groups.

These mother tongues demand the postfix of 'lah's, and that extends into their version of English. So let's look into what the use of 'lah's do to the collective psyches, positively or otherwise.

The utility of 'lah's is about assertions. Once used, it's implicit that there should be no more questions.

Given that 80% of sentences uttered here involves food, let's consider "This noodle is overcooked lah!" Not only does that mean the noodle is subjectively overcooked, it is objectively true without a benefit of doubt. Along with that the speaker is also saying "how stupid are they to overcook this mutton?" That is how much content 'lah' is able to compress.

To raise questions following a 'lah' amounts to declaration of war.

Without questions there's no fear uncertainty and doubt.

Coincidentally so do inquiries. Without inquiry, truth has no chance to emerge.

So why is Manglish compelled to append 'lah's in their usage? One non-answer is the need to be consistent with the people's native tongue (Bahasa, Chinese, Tamil, etc). The fact that a postfix transcends languages is even more the reason why it calls for examination on its importance in the eyes of its users.

Side note: Chinese also appends 'loh's to sentences, which is not at all the same with 'lah's. 'Loh' too is assertive but it's almost apologetic about it.

I'll venture some simple guesses first. It's a simple way to reach the comfort zone of certainty. "This is expensive lah!" is more impactful than "This is expensive." Sounding uncertain will have you walked over like a doormat.

Another related speculation is the premium people place on being right. Suppose I say "two plus two is five," I'll be dismissed without a second look. But "two plus two equals five lah!", that is conviction so total you cannot ignore. In this scenario language-users prioritize reaching social validation over objective truth. If this guess is correct, it may mean that being socially right was a matter of life and death in the past, which the attitude passes on for generations.

But I'm ultimately doubtful about the speculations above. I lean towards theories that speak to the social factors.

What if 'lah's is the way for different language-speakers to signal the end of an assertion? Because nobody really understand each other given their poor commands on most languages, it's never clear to the listener if the speaker is finished until 'lah' is uttered.

Consider two people talking. One says: "I want to eat nasi lemak..." and stops. The other will be wondering if there are other incoming choices for lunch and prep his mind to anticipate alternatives. Such trivial amount of cognitive load throughout the day adds up.

Had the sentence ended with "I want to eat nasi lemak lah," the other person can head straight into dispute mode by arguing for what he prefers instead without being wishy-washy.

The faster a conversation ends, the less room there is for dispute. That way convos need not go deep but go for breath instead. The effect is such that most convos are shaped like a fat and short T.

The common denominator above is that nobody really understands each other. 'Lah' accelerates that, making sure there's no chance for mutual understanding but just enough comprehension for fist fights to not break out.

'Lah's are not likely to go away in Manglish. In fact I foresee it'll only grow.

'Lah's make conversations a Carse-ian finite game. Whoever reaches 'lah' first wins.

I hope I'm wrong; being wrong here doesn't cost anything. I hope someone calls me elitist and presents the case for 'lah's and its benefits.