Well, at least it wasn't the 'e' key - that is a specific writing challenge that seems like a different pain in the butt. But I can't say it's exact name because it has the denied letter! But as it excludes it's banned letter, perhaps we can swap and call this exercise a lipegram instead. Considering the exact meaning, this may still be the unnamable thing (referencing texts defining Enlgish terms), as it can technically exclude any single letter. It is usually 'e', but that is not required.