@subtext What degree and kind of silliness are you looking for? Merely not useful to adventurers, embarrassing in some way, implausible that they’d even exist…?
I like things that players would have fun with, but aren’t “useful” in the sense that it becomes a utility item they’re using every game. Something that can be a joke!
Not against items that have use either
@subtext
Rod of Tattoos: As an attack, you can point this rod at someone within 30’ and imagine a still image on an exposed patch of that person’s skin. This will cause the desired image to appear on the person’s skin for 1 minute.
If you maintain concentration on the effect for the full minute, without the rod leaving your grasp and without you or the subject leaving range of each other, the image becomes permanent, unless removed by Remove Curse.
The rod functions up to three times per day.