ISTT 

I speak the truth.

Sometimes written as, 'ISTTN' (I speak the truth, Nigger!)

Guy one: Ashlyn has a nice ass.

Guy two: That's my girlfriend, bitch.

Guy one: Calm down man! ISTT.

ISTT by I'm Amy May 9, 2011

istts 

I Swear To Taylor Swift
Term mainly used by swifties to express that you are honest. Another way of saying istg (I Swear To God).

-Did you see that girl? She is mentally ill…
- I should’ve noticed that. I heard her use “istts”

istts by caroldanversenthusiast November 29, 2021

Istth

I
Swear
To
The
Hamsters

A phrase to use in front of your strict Irish Catholic family that don't want you to swear at God.

A: look at him, guarding his students.

M: He's such a dad Istth

Istth by DadzawaIsBae December 30, 2019

isttgl 

I swear to the good lord

A gentler alternative to stg

Girl 1: Trevor hasnt texted me back in 6 hours, if hes not doing anything important isttgl this is my Last straw with him

Girl 2: oh relax, hes right here next to me

Girl 1: next to you? Oh isttgl

isttgl by castiels bushes of love March 13, 2020

Istta 

An acronym meaning "I swear to the Archons". This can be used for those playing Genshin Impact, an open world exploration game. It is a customized version of "istg" or "I swear to God."

Lucy: is being annoying*
Jenna: Istta if this girl doesn't quit it.

Istta by SaplingOfTruth January 13, 2022

Isttlofg

I means 'I swear to the Lord our fuking god'

Jane:isttlofg ur gonna kill urself one day

Isttlofg by Bipanicbish March 12, 2022

Isttyhif 

I’m scared to tell you how I feel

You: isttyhif
Crush: huh ??
You: nothing

Isttyhif by HesFlint May 12, 2022