punji stick
Concise Oxford English Dictionary © 2008 Oxford University Press:
punji stick /ˈpʌndʒi/
▶noun (especially in SE Asia) a sharpened, typically poison-tipped bamboo stake set in a camouflaged hole in the ground as a means of defence.
– origin C19: punji prob. of Tibeto-Burman origin.
'punji stick' also found in these Oxford entries:

