Plurals: Name Yr Favorites

Let’s start with
corpus -> corpora (although corpus(s)es is okay too?)

The singular of scampi is scampo, so that's something.

Someone asked me what the plural of Twix was, and well, it's Twixes, but I had fun trying to think of alternatives like "Twisteces"

Radii
Courts martial

In my experience everyone says 'mediums' these days when talking about art materials.