I'm with Lady Dark Angel and two subs.

We have them lay on the floor, with nettles across their crotch.

We're going to let them jerk, we're going to let them have release.

But, well, as well as grabbing their cocks they're going to also have to grab a handful of nettles, bringing pain with each stroke.

We're not sure they're suffering enough so, join in to make sure they feel the pain.