A fellow named Kim in Pyongyang/

Created a very big bang/

With stuff that is fissile*/

To put on a missile/

And said “See the size of my whang!”///

*I am indebted to @Souris_Verte for pointing out that if, as North Korea claims, the bomb tested was an H-bomb, it uses fusion, not fission. So I must fall back on the fact that experts have doubted this claim (and, of course, poetic licence).  https://twitter.com/Souris_Verte/status/904397630595371010