If you spend any time on social media, texting, or reading online conversations, you’ve probably come across the abbreviation ISTG. Short for “I Swear To God,” it’s one of the internet’s go-to acronyms to express strong emotion—especially frustration, seriousness, or promise.
But like all expressive phrases, ISTG can be intense or even come off too strong in certain contexts. Depending on your tone, mood, or audience, it might be better to use a different acronym or phrase to convey your feelings.
In this article, we’ll break down the core meaning of ISTG, and explore 30 alternative acronyms and expressions—each tailored for different situations and emotional tones. From playful to serious, you’ll get the right phrase for every vibe.
🔍 What Does “ISTG” Mean?
ISTG stands for:
I Swear To God
It’s most commonly used in texting and online chats, and it’s usually a reactionary phrase that means:
- “I’m serious right now.”
- “I’m not lying.”
- “I’m fed up.”
- “I mean it.”
It can express exasperation, a serious promise, or anger, and is often used with exaggeration or humor, depending on the tone:
- “ISTG if my Wi-Fi goes out again…”
- “ISTG that movie changed my life.”
But ISTG isn’t always the right fit. Sometimes it’s too dramatic, too religious, or just doesn’t suit the setting. That’s where alternatives come in.
đź’¬ 30 Alternatives to ISTG (and When to Use Them)
Here are 30 acronyms, phrases, and expressions that work in place of ISTG, each with examples and context tips.
1. Fr (For Real)
Used to emphasize honesty or seriousness.
Use when you’re casually confirming something.
“That was the best pizza I’ve ever had, fr.”
2. No Cap
A slang phrase meaning “no lie” or “I’m not joking.”
Use in Gen Z or casual circles.
“No cap, that test was brutal.”
3. Deadass
Intensely serious or sincere, especially in NYC slang.
Use for emphasis with attitude.
“Deadass, I’m not going.”
4. Tbh (To Be Honest)
Expresses honesty, often used to soften or clarify.
Use in more thoughtful or honest conversations.
“Tbh, I didn’t enjoy the movie.”
5. IDK but I swear…
A casual version of ISTG.
Use for uncertainty mixed with sincerity.
“Idk but I swear I left my keys here.”
6. I Promise
Straightforward, with a softer tone than ISTG.
Use in earnest or heartfelt moments.
“I promise I won’t tell anyone.”
7. Legit
Short for “legitimately,” expressing truth.
Use in casual affirmations.
“That was legit scary.”
8. Swear Down
UK slang for making a serious promise.
Use for emphasis in British English.
“Swear down, I didn’t do it.”
9. Mark My Words
A dramatic but formal alternative.
Use for predictions or threats.
“Mark my words, he’ll regret it.”
10. On God
Strong affirmation, often used seriously or dramatically.
Use when you want to stress sincerity or frustration.
“On God, I’m not lying.”
11. Bet
Short and confident agreement.
Use for casual affirmation or challenge.
“You think I won’t? Bet.”
12. Scout’s Honor
Old-school phrase suggesting honest intention.
Use in lighthearted, playful contexts.
“I didn’t peek, scout’s honor!”
13. You Have My Word
More formal and sincere.
Use in trust-building conversations.
“You have my word, I’ll be there.”
14. Bruh I Mean It
Adds humor but keeps it serious.
Use for exaggerated frustration or disbelief.
“Bruh I mean it, that was wild.”
15. Real Talk
Introduces honesty or sincerity.
Use when switching to a serious tone.
“Real talk, I need help.”
16. As God Is My Witness
Old-fashioned, very serious.
Use for dramatic storytelling or promises.
“As God is my witness, I’ll never do that again.”
17. Cross My Heart
A sweet and sincere promise.
Use in emotional or childlike contexts.
“Cross my heart, I won’t tell.”
18. Forreal Forreal (Fr Fr)
Emphasizes absolute truth.
Use for extra seriousness.
“Fr fr, I’m done with that app.”
19. Swear It
Short, flexible version.
Use casually.
“Swear it’s true?”
20. No Lie
Direct and emphatic.
Use for believable or shocking statements.
“No lie, it really happened.”
21. Lowkey Swear
Adds subtlety or humor.
Use for laid-back emphasis.
“Lowkey swear I saw her at the mall.”
22. On Everything
High-intensity swear of sincerity.
Use in emotional or passionate contexts.
“On everything, I would never.”
23. I Vow
More poetic or formal.
Use in romantic or deep emotional contexts.
“I vow to protect you.”
24. For Real Tho
Adds emphasis and a chill tone.
Use for disbelief or sincerity.
“For real tho, that twist was wild.”
25. Trust Me
Simple and strong.
Use when credibility is key.
“Trust me, it’s not what you think.”
26. I Swear On My Life
Intense and deeply personal.
Use sparingly, when extremely serious.
“I swear on my life I didn’t know.”
27. No Joke
Adds urgency or gravity.
Use when making a serious claim.
“No joke, I almost fell asleep driving.”
28. You Gotta Believe Me
Used when seeking trust.
Use when trying to gain someone’s confidence.
“You gotta believe me, I had no idea.”
29. I’m Not Even Playing
Emphatic but playful.
Use in light but sincere contexts.
“I’m not even playing, I’m serious.”
30. On My Mama
Culturally expressive swear of truth.
Use in slang-heavy or emotional speech.
“On my mama, I didn’t touch it.”
🧠When to Use (or Avoid) ISTG and Its Alternatives
- Use ISTG when you’re expressing urgency, seriousness, or emotional emphasis in casual conversations.
- Avoid ISTG in professional, religious-sensitive, or formal settings—it might sound too dramatic or inappropriate.
- Choose “I Promise,” “You Have My Word,” or “Trust Me” in respectful or formal settings.
- Use “Fr,” “No Cap,” “Deadass,” or “On God” for friends or social media where tone is casual or emotional.
- Cultural tip: Some phrases like “On My Mama” or “On God” carry strong cultural weight—use with understanding and respect.
âś… Final Thoughts
Whether you’re hyping something up, venting frustration, or making a heartfelt promise, there’s always more than one way to say “ISTG.” Choosing the right alternative not only strengthens your message—it makes sure your tone lands exactly the way you want it to.
So next time you feel an ISTG bubbling up, pause and pick the acronym (or phrase) that truly fits the vibe.
