Removes magic numbers and an useless check

- it shouldn’t runtime.

code/game/objects/effects/effect_system.dm

@@ -846,7 +846,7 @@ steam.start() -- spawns the effect
 
 	if (istype(AM, /mob/living/carbon))
 		var/mob/living/carbon/M = AM
-		M.slip(5, 2, src, 1)
+		M.slip(5, 2, src)
 
 
 /datum/effect/effect/system/foam_spread

code/game/objects/items/devices/PDA/PDA.dm

@@ -961,7 +961,7 @@ var/global/list/obj/item/device/pda/PDAs = list()
 /obj/item/device/pda/clown/Crossed(AM as mob|obj) //Clown PDA is slippery.
 	if (istype(AM, /mob/living/carbon))
 		var/mob/living/carbon/M = AM
-		if(M.slip(8, 5, src))
+		if(M.slip(8, 5, src, NO_SLIP_WHEN_WALKING))
 			if (ishuman(M) && (M.real_name != src.owner))
 				if (istype(src.cartridge, /obj/item/weapon/cartridge/clown))
 					var/obj/item/weapon/cartridge/clown/cart = src.cartridge

code/game/objects/items/weapons/clown_items.dm

@@ -11,7 +11,7 @@
 /obj/item/weapon/bananapeel/Crossed(AM as mob|obj)
 	if (istype(AM, /mob/living/carbon))
 		var/mob/living/carbon/M = AM
-		M.slip(4, 2, src, 1)
+		M.slip(4, 2, src)
 
 
 /*
@@ -20,7 +20,7 @@
 /obj/item/weapon/soap/Crossed(AM as mob|obj) //EXACTLY the same as bananapeel for now, so it makes sense to put it in the same dm -- Urist
 	if (istype(AM, /mob/living/carbon))
 		var/mob/living/carbon/M = AM
-		M.slip(3, 2, src, 1)
+		M.slip(3, 2, src)
 
 /obj/item/weapon/soap/afterattack(atom/target, mob/user as mob, proximity)
 	if(!proximity) return