Yeah. I'm imagining a suicide bomber wearing a huge fat suit like Mike Myers wore when played Fat Bastard. Just a giant fake belly with a literal nuclear bomb concealed inside.

Though really, I think the real problem with a "nuclear suicide vest" is simple practicality. Like, what's the actual point? The whole point of a suicide vest is to be able to smuggle explosives into an area where they'll do the most damage. A guy holding a bomb in his hands won't be let into a crowded bus. Someone holding a pipe bomb is going to cause people to run away from them screaming. A suicide vest bomber seeks to sneak into a crowded space densely packed with many people. Suicide bombers need to get close to large numbers of people. They need a bomb that can be concealed on their person. Otherwise they end up doing no more damage than someone could with a handgun.

But a nuke? You don't need to sneak the nuke into the stadium. You set it off five blocks away. It doesn't need to be concealed. If you want to deliver a terrorist nuking, you would instead load it on the back of a truck with heavy radiation shielding. You don't try to sneak it in to a crowded location. You just try to drive it into a dense urban area or near a critical piece of infrastructure and hope to not set off any radiation detectors along the way. A nuclear truck bomb is a reasonable fear. A nuclear suicide vest is laughable.