Soap, you can use it on items. Used a few times it will clean any coloring off of an item. Used a few more times, the item becomes really shiny. Use the soap a lot more times, the item becomes extremely slippery
You can also eat the soap. Ypu wouldnt want to eat the soap, you will get severe radiation, but if you do when you talk your mouth works like a bubblegun.
You can also put it in a crossbow or something to shoot at people and cleanse them.
You can also drop the soap and watch it slide across the ground.
Overall it would kind of just be a nice item for customization.