This makes for considerable humor, which Jacobs-Jenkins — with his ear for the snark of 38-year-olds (like himself) — renders faultlessly, and which Ting’s breakneck staging, never missing the details, amps to the max. It’s a mystery of the fine writing and excellent acting that the humor does not squash but rather enhances the pathos surging underneath. When it erupts, it can be devastating.