I want to send an inappropriate masochistic 9/11 joke to a sensitive friend
Are you sure you want to make such a tasteless joke involving a tragedy?
I'm careful with the things I say to people.
You shouldn't joke about a tragedy. You could upset someone who may have a person connection to said tragedy. You'll also gain a reputation of being insensitive.
I want to hurt other people's feelings.
Instead of hurting your sensitive friend find something else to do. Use your sense of humor to make non-offensive jokes that other people also could enjoy.