adds ability to set organs as unremovable

code/__DEFINES/obj_flags.dm

@@ -59,6 +59,7 @@
 #define ORGAN_VITAL				(1<<4)	//Currently only the brain
 #define ORGAN_EDIBLE			(1<<5)	//is a snack? :D
 #define ORGAN_SYNTHETIC_EMP		(1<<6)	//Synthetic organ affected by an EMP. Deteriorates over time.
+#define ORGAN_UNREMOVABLE		(1<<7)	//Can't be removed using surgery
 
 /// Integrity defines for clothing (not flags but close enough)
 #define CLOTHING_PRISTINE	0 // We have no damage on the clothing

code/modules/surgery/organ_manipulation.dm

@@ -119,8 +119,8 @@
 				I = organs[I]
 				if(!I)
 					return -1
-				if(istype(I, /obj/item/organ/tongue/tied)) //Since I couldn't find any code for unremovable organs
-					to_chat(user, "<span class='warning'>Only Alexander the Great would be able to untie that knot!</span>")
+				if(I.organ_flags & ORGAN_UNREMOVABLE)
+					to_chat(user, "<span class='warning'>[I] is too well connected to take out!</span>")
 					return -1
 				display_results(user, target, "<span class='notice'>You begin to extract [I] from [target]'s [parse_zone(target_zone)]...</span>",
 					"<span class='notice'>[user] begins to extract [I] from [target]'s [parse_zone(target_zone)].</span>",

code/modules/surgery/organs/tongue.dm

@@ -326,6 +326,7 @@
 	say_mod = "signs"
 	icon_state = "tonguetied"
 	modifies_speech = TRUE
+	organ_flags = ORGAN_UNREMOVABLE
 
 /obj/item/organ/tongue/tied/Insert(mob/living/carbon/M)
 	. = ..()