Not a stupid question! This is something I've thought about too, for me I think it would lessen the guilt for loved ones.
My ideas are usually regarding something dangerous/deadly, but where they would think "oh he didn't mean to CTB he was just doing something dangerous and stupid". Some people might think I was an idiot, but that's better than having my family know I CTB on purpose.
Since I'm planning on moving out ASAP, I want to set up a chemistry lab, AND My family knows about that, I figure I'll "accidentally" poison myself with cyanide or hydrogen sulfide or something. Some other ideas would be like, single-vehicle car crash; nobody knows if you fell asleep, mechanical failure happened, etc.
So I guess "plausible deniability" is the factor here; do something on purpose that could also be interpreted as an accident, and you can have it both ways!