Apparently mojang uses the entity id -1 in some packets. May as well use -10

src/me/libraryaddict/disguise/DisguiseAPI.java

@@ -291,11 +291,11 @@ public class DisguiseAPI {
      */
     @Deprecated
     public static int getFakeDisguise(UUID entityId) {
-        return -1;
+        return -10;
     }
 
     public static int getSelfDisguiseId() {
-        return -1;
+        return -10;
     }
 
     /**