[laverya]

Or the nuke does an intentional fizzle (sets off the implosion in an intentionally asymmetric manner resulting in plutonium being spread all over, but no nuclear criticality) which seems like the most serious-but-still-plausible "fuck you for trying this" mechanism I can think of.

[Accujack]

A fizzle is just a nuclear weapon that doesn't reach its design potential yield, which isn't the same thing as no nuclear criticality.

A 5 MT hydrogen bomb that "only" yields 750 kt of explosive power is a fizzle, but you don't want to be anywhere near when it happens.

[laverya]

Yeah, fizzle was a bad choice of word. I'm not sure what you'd call an intentionally subcritical detonation, though.