So this is coming up because in a game in the past, I thwarted an enemy's attempt to turn invisible and flee from us by basically rolling a high enough perception check to watch the trail of grass squishing as he stepped on it, and then splashing him with a bottle of writing ink. The DM allowed it, and we chased after the floating Rorschach Test. But this got me thinking about what would work for this.

So my question is, if a creature is already invisible, such as by the spell, would things thrown onto it then become invisible as well?

Now, I'm guessing this would work for most games in general, but I was playing 5e D&D in particular, so I'm going to cite the spell from that edition's book.

The spells says:

A creature you touch becomes invisible until the spell ends. Anything the target is wearing or carrying is invisible as long as it is on the target's person. (PHB, 254)

While it doesn't specifically state it, one would assume that anything the target puts on or picks up during the spell's duration would become invisible as well. So the issue then becomes what would be considered "worn".

NI would assume that if the target were, say, set on fire, the spell would not make the fire become invisible. I could also see the ink working, because it is not wearing the ink, with possibly the ink that soaks into clothing turning invisible.

But what about, say, throwing a sheet or a net onto an invisible target? Would they be considered wearing it, turning it invisible as well? Or would you just see an sheet or net hanging there in the air?