Two config variables added - disable_player_mice and uneducated_mice. The first, if enabled, prevents players from spawning as mice, and the second, if enabled, prevents mice from understanding human speech (which they now do my default)

universal_understand = 1 now allows player-controlled mobs to understand what everybody is saying without necessarily allowing them to talk back intelligibly. Mice have universal_understand = 1 by default.

code/modules/mob/dead/observer/observer.dm

@@ -293,6 +293,10 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 	set name = "Become mouse"
 	set category = "Ghost"
 
+	if(config.disable_player_mice)
+		src << "<span class='warning'>Spawning as a mouse is currently disabled.</span>"
+		return
+
 	var/timedifference = world.time - client.time_died_as_mouse
 	if(client.time_died_as_mouse && timedifference <= mouse_respawn_time * 600)
 		var/timedifference_text
@@ -302,7 +306,7 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 
 	var/response = alert(src, "Are you -sure- you want to become a mouse?","Are you sure you want to squeek?","Squeek!","Nope!")
 	if(response != "Squeek!") return  //Hit the wrong key...again.
-	
+
 
 	//find a viable mouse candidate
 	var/mob/living/simple_animal/mouse/host
@@ -318,6 +322,8 @@ This is the proc mobs get to turn into a ghost. Forked from ghostize due to comp
 		src << "<span class='warning'>Unable to find any unwelded vents to spawn mice at.</span>"
 
 	if(host)
+		if(config.uneducated_mice)
+			host.universal_understand = 0
 		host.ckey = src.ckey
 		host << "<span class='info'>You are now a mouse. Try to avoid interaction with players, and do not give hints away that you are more than a simple rodent.</span>"