Those With a Collection, What is the Most Unique Sleeve You Own?

Recently, I had brought out a few different sleeves in one of my last sessions and was swapping between them rapidly. It got me to realize how unique the opening tentacle section in Lvl Up feels compared to the other sleeves I was using. This has me wanting to ask others with more/different sleeves than me:

What is the most unique sleeve in your collection? Can be for good or bad reasons, but what's the one you find to be most unlike the others sensation-wise and why?