The vibrator of slicing.
This is a knife with two saw-like blades that move back and forth, allowing enhanced slicing of cooked or raw meats.
It gives advantage on all intimidate checks, with a +2 if wearing fishnets and/or high heels
I always try to have 2 Immovable Rods with my character so I basically have an infinite ladder. You can lock and unlock each rod and use them like rungs to climb things, cross gaps, etc. And they’re not really rare or expensive.
Maybe add the opposite of those; rods that never stop moving. Unstoppable Rods.
Deck of too many things, it’s a deck of regular playing cards that constantly vomits playing cards when opened.
A DM once gave me a necklace that could only be worn by neutral or worse alignments, and with a thought it would cause a torrential downpour of blood. The blood required a constitution check to prevent characters from puking. That was a pretty neat item.
Book of secrets. When opened, the book displays a secret whispered in the last minute, at least 50 miles away, somewhere on this plane.