Merge branch 'master' of https://github.com/Citadel-Station-13/Citadel-Station-13 into upstream-merge-33783

# Conflicts:
#	_maps/map_files/generic/CentCom.dmm
#	code/modules/mob/living/living.dm

code/modules/holiday/holidays.dm

@@ -394,6 +394,17 @@ Since Ramadan is an entire month that lasts 29.5 days on average, the start and
 /datum/holiday/xmas/greet()
 	return "Have a merry Christmas!"
 
+/datum/holiday/xmas/celebrate()
+	SSticker.OnRoundstart(CALLBACK(src, .proc/roundstart_celebrate))
+
+/datum/holiday/xmas/proc/roundstart_celebrate()
+	for(var/obj/machinery/computer/security/telescreen/entertainment/Monitor in GLOB.machines)
+		Monitor.icon_state = "entertainment_xmas"
+
+	for(var/mob/living/simple_animal/pet/dog/corgi/Ian/Ian in GLOB.mob_living_list)
+		Ian.place_on_head(new /obj/item/clothing/head/helmet/space/santahat(Ian))
+
+
 /datum/holiday/festive_season
 	name = FESTIVE_SEASON
 	begin_day = 1