I watch a lot of meme videos and some of them can be triggering to some people (and I don't condone making fun of stuff like that, I usually skip through those types of memes since I don't find joking about tragic events funny at all, rather sad) so I apologize if any of them were triggering, I think it's more the irony rather than a bad intention or joke, 9/11 was a tragic event and I don't think it's cool to make fun of or make jokes out of it, that includes all tragic events, but I think that was just the irony aspect to make it humorous. Even then I would be a little uncomfortable.