Who lives in a pineapple under the sea? The people that sunk with the titanic.
Why did the Titanic sink?
I mean the people died because James Cameron screwed it up. I don't care about them.
The sinking of Titanic was a traumatizing event for many people and it can be triggering to even talk about it to some people who have experienced similar events much less joke about. Making light about it can be hurtful, just like you would be hurt if people made a joke about something that caused you pain.