When a animation like "Acts_AidlPercMstpSlowWrflDnon_pissing" is performed on a player unit the unit just stays still with holstered weapon if a weapon is present. It won't work with any kind of command. I tried [playMove, switchMove,playAction,playActionNow,playGesture].
A AI unit is performing the animation as displayed in the animation selection gui.
It's not only in SP. In MP you can see others doing the anim but for yourself you just stand there like a fool.