throw at mobs laying down

code/game/atoms.dm

@@ -686,13 +686,29 @@
 	SEND_SIGNAL(src, COMSIG_ATOM_FIRE_ACT, exposed_temperature, exposed_volume)
 	return
 
-/atom/proc/hitby(atom/movable/AM, skipcatch, hitpush, blocked, datum/thrownthing/throwingdatum)
-	if(density && !has_gravity(AM)) //thrown stuff bounces off dense stuff in no grav, unless the thrown stuff ends up inside what it hit(embedding, bola, etc...).
-		addtimer(CALLBACK(src, .proc/hitby_react, AM), 2)
+/**
+ * React to being hit by a thrown object
+ *
+ * Default behaviour is to call [hitby_react][/atom/proc/hitby_react] on ourselves after 2 seconds if we are dense
+ * and under normal gravity.
+ *
+ * Im not sure why this the case, maybe to prevent lots of hitby's if the thrown object is
+ * deleted shortly after hitting something (during explosions or other massive events that
+ * throw lots of items around - singularity being a notable example)
+ */
+/atom/proc/hitby(atom/movable/hitting_atom, skipcatch, hitpush, blocked, datum/thrownthing/throwingdatum)
+	SEND_SIGNAL(src, COMSIG_ATOM_HITBY, hitting_atom, skipcatch, hitpush, blocked, throwingdatum)
+	if(density && !has_gravity(hitting_atom)) //thrown stuff bounces off dense stuff in no grav, unless the thrown stuff ends up inside what it hit(embedding, bola, etc...).
+		addtimer(CALLBACK(src, .proc/hitby_react, hitting_atom), 2)
 
-/atom/proc/hitby_react(atom/movable/AM)
-	if(AM && isturf(AM.loc))
-		step(AM, turn(AM.dir, 180))
+/**
+ * We have have actually hit the passed in atom
+ *
+ * Default behaviour is to move back from the item that hit us
+ */
+/atom/proc/hitby_react(atom/movable/harmed_atom)
+	if(harmed_atom && isturf(harmed_atom.loc))
+		step(harmed_atom, turn(harmed_atom.dir, 180))
 
 /atom/proc/handle_slip(mob/living/carbon/C, knockdown_amount, obj/O, lube)
 	return