Add on_slip procs to liquid contents + hypodermic prickles gene

AKA makes plants squash on slip, and sting on slip

code/modules/hydroponics/plant_genes.dm

@@ -179,6 +179,10 @@
 	// For code, see grown.dm
 	name = "Liquid Contents"
 	examine_line = "<span class='info'>It has a lot of liquid contents inside.</span>"
+
+/datum/plant_gene/trait/squash/on_slip(obj/item/reagent_containers/food/snacks/grown/G, mob/living/carbon/C)
+	// Squash the plant on slip.
+	G.squash(C)
 
 /datum/plant_gene/trait/slip
 	// Makes plant slippery, unless it has a grown-type trash. Then the trash gets slippery.
@@ -367,6 +371,9 @@
 /datum/plant_gene/trait/stinging
 	name = "Hypodermic Prickles"
 
+/datum/plant_gene/trait/stinging/on_slip(obj/item/reagent_containers/food/snacks/grown/G, atom/target)
+	on_throw_impact(G, target)
+
 /datum/plant_gene/trait/stinging/on_throw_impact(obj/item/reagent_containers/food/snacks/grown/G, atom/target)
 	if(isliving(target) && G.reagents && G.reagents.total_volume)
 		var/mob/living/L = target