#3778
vanilla
You can quaff an adjacent water elemental, giving you a YAFM (“The water elemental looks deeply offended.”) and angering it if it was peaceful. Drinking it does not have any effect on you, but deals 1 HP damage to the elemental, killing it if it was at 1 HP (“As you drink the water elemental, it disintegrates into droplets.”)
You can also dip potions into a water elemental to dilute them, which also produces the offended message and angers it, but does not do any potion effect or damage to it.