Definition & Meaning of "ISTFG"

Usage of ISTFG

I swear to f**king god (ISTFG) is an abbreviation used to express exasperation, disbelief, or agreement. This phrase can be used to swear truthfully without having to use a more serious swear word, such as the word "God". For example, three sample text messages using the abbreviation ISTFG could be:

1. Person1: I'm so exhausted.
Person2: ISTFG, me too.

2. Person1: I can't believe what happened.
Person2: ISTFG.

3. Person1: I'll do it for sure.
Person2: You got it, ISTFG.