“Everyone gets sick.” Noah Diaz has written an oblique, daring play about what happens when our bodies betray us and we begin to disappear. YOU WILL GET SICK is unusual both structurally and because it’s the rare play that feels substantive even as it’s brief (75 minutes). The strange, phantasmagoric proceedings here are also tender and, by the end, surprisingly moving. The play depicts our demise as a kind of swoon and, finally, a reunion. It’s loss that brings us home. The wonder is how we struggle to not get there. Diaz is just 29 which maybe makes YOU WILL GET SICK even more satisfying. Oh, and at the other end of the age spectrum, Linda Lavin remains, at 85, a treasure.