Woman in business attire making swearing gesture.

One of the hottest internet acronyms among today’s teenagers is ISTG. Here’s what this versatile slang term means and how you can use it in your messages and social media posts.

ISTG is short for “I swear to God.” It can express that you’re being serious and truthful, or that you have strong feelings—typicaly either excitement or frustration.

I Swear to God

ISTG means “I swear to God.” It’s an acronym that people use in online conversations and internet posts to assure others, express annoyance, or convey how strongly they feel about something. You’ll find it all over the internet, from social media platforms like Twitter and Instagram to direct messages between friends.

You can write this acronym in the lowercase “istg” and the uppercase “ISTG.” These two are essentially interchangeable. However, the all-caps version may seem more “intense,” depending on the context.

The Origin of ISTG

Unlike other internet acronyms that started in the 90s, ISTG likely originated in the early 2000s. As teenagers began getting internet access, instant messaging programs like AOL Instant Messenger and Yahoo Messenger rose in popularity. This came with an entirely new set of acronyms from common phrases used by teenagers at the time.

The first definition for ISTG on the internet slang repository Urban Dictionary was created in 2007 and reads, “I swear to God. Promising.” ISTG became even more popular in the late 2010s with its use in messaging apps like Snapchat and WhatsApp. Nowadays, you can find this acronym all over the internet.

Annoyance and Assurance

There are two common ways to use ISTG in your messages, with the meaning largely depending on the context of the conversation. It can either signify that you’re frustrated or that you’re trying to be honest. Since these are two distinct meanings, you should avoid confusing the two. For example, you might not want to send a chipper response if your friend is annoyed at the entire conversation.

First, the acronym can show that you’re frustrated or annoyed at something. Normally, an “annoyed” ISTG is delivered with a sarcastic joke or a hint of someone’s annoyance, such as the word “ugh.” For example, someone might tweet out, “Ugh, istg if this rain doesn’t end soon,” to signal that they’re not a fan of the bad weather. The message might also seem particularly brusque, such as a sentence that reads “ISTG…” with ellipses being a common sign of frustration.

The other conveys that you’re being sincere or vouching that something is true. You could use this if you’re trying to describe something that seems unbelievable or if other people express doubts about your story. If you’re trying to convince others of a supernatural encounter, you might say, “ISTG! I saw a ghost!”

Another ISTG

There’s another way to use this slang term that’s become increasingly popular in the social media age. It’s what we call an “emphatic” ISTG. People often use this on social apps, such as Twitter and Instagram, to convey that they feel very strongly about something.

This definition normally skews very positively, with people using it to describe how much they enjoyed something. You might use this to express your opinions on an album you just listened to or a movie that you just watched. For example, if you enjoyed a recent show on Netflix, you might say, “ISTG, this new show is amazing.”

You can also use it to emphasize opinions that, while not unpopular, might be contentious to some. These are also called “hot takes” — thoughts that inspire a lot of discussion and debate. For example, if you love Hawaiian pizza, you might Tweet out, “ISTG pineapples belong on pizza.”

How to Use ISTG

ISTG has several definitions that you can deploy in different contexts. You can use it to express your deep frustration, vouch that something is true, or emphasize your beliefs. It can be written in both the lowercase “istg” and the uppercase “ISTG” interchangeably. Since this is a very casual acronym, avoid using it in business or professional scenarios.

Here are a few examples of ISTG in action:

  • “Ugh, istg, I’m going to lose my mind at work.”
  • “ISTG, I’m telling the truth. I won the lottery!”
  • “Istg, this is the best album I’ve ever heard.”
  • “If you don’t stop being reckless, istg you’re going to break a leg.”

Do you want to learn about some other internet slang terms? Check out our explainers on TTYL, RN, and TMI. You’ll have a complete internet vocabulary soon enough!

RELATED: What Does "TMI" Mean, and How Do You Use It?

Profile Photo for Vann Vicente Vann Vicente
Vann Vicente has been a technology writer for four years, with a focus on explainers geared towards average consumers. He also works as a digital marketer for a regional e-commerce website. He's invested in internet culture, social media, and how people interact with the web.
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