Exclamation mark
From Wikislippy
An exclamation mark or exclamation point is a punctuation mark: ! It is usually used after an interjection or exclamation to indicate strong feelings or high volume, and often marks the end of a sentence.
Sarcasm
In writing and often subtitles, especially in British English, a (!) symbol (an exclamation mark within brackets) implies that a character has made an obviously sarcastic comment eg: "Ooh, a sarcasm detector. Oh, that's a really useful invention(!)"
