When did it become acceptable to joke about 9/11?

For many people in their late teens and early twenties, 9/11 belongs to history, not memory. (Picture: Getty/Metro)

Search the darker corners of the internet and you’ll find jokes about almost any major event almost immediately. 

Yet some tragedies seem, at least for a while, too enormous, too raw or too culturally significant to become punchlines.

For many people in their late teens and early twenties, 9/11 belongs to history, not memory.

Many were years away from being born when the Twin Towers fell, and some first encountered the attacks through memes, television shows or social media before they l...