It seems like a topical sort of topic, what with the President of the United States expressing his opinions on holes and fecal waste. So you might be wondering, “where is the shithole of an octopus or squid?” I am here to tell you.
The cephalopod anus is inside the mantle cavity, a ways behind the siphon.
The siphon, of course, is that prominent funnel that they also use for jet propulsion. So sure, they can squirt poop right out that big hole when they jet away.
Now you know.