(as) dry as a desert

1. Completely or exceptionally dry. Man, it is as dry as a desert out there today—not a bit of humidity in the air. And if that floor isn't as dry as a desert when you're done, make sure to put up the signs—we don't need anyone slipping out here! My skin always gets as dry as a desert in the winter. No amount of moisturizer ever seems to help!

2. Having or characterized by extremely unemotional, understated, straight-faced humor. The legendary comedian was known for his distinct appearance and jokes that were always dry as a desert. It's a typical black comedy—edgy, uncomfortable, and as dry as a desert. Don't take anything my grandfather says seriously. His humor is just dry as a desert.