Doggerel for The Grunt

I got the '*****' with panji pits,
When in Vietnam.
Pits they dug both round and square,
Whatever shape, the things were there,
'Cammed' to look just like the ground,
Crouching there until, when found,
Springy stakes of poisoned wood
Would pierce the finder's legs right good.
Then, liberal smears of faecal stuff,
Would swell the limb and make it puff,
Turn purple, yellow, awful stuff.
Requiring treatment PDQ.,
While thanking God it wasn’t you.
No - panji pits
Gave me - the '*****.'