A young man at the coffee shop extended his fist toward me, and I stood before it without any idea of the protocol. A closed fist. Offered gently. Held in the air between us, patient, expecting something. In my training, a raised fist has a short list of meanings, and none of them end in friendship. But his face was open and pleased — he had just handed me my order — so I understood this was a CEREMONY, and I was failing it in real time. I placed my coffee down and gripped his fist with both hands, as one accepts a precious gift. He laughed — kindly, I want that recorded — and said, "No man, like this," and guided me: knuckles, meeting knuckles, one soft tap. Then his hand sprang open and pulled away, fingers spread, with a quiet "pssshh." THE EXPLOSION. There is an EXPLOSION at the end, completely optional and completely essential, and no document in this entire country warns you about it. I have since charted the full taxonomy, because no one else has bothered: the FIST BUMP (respect, brief, hygienic, the workhorse), the HIGH FIVE (triumph, loud, requires commitment), the HANDSHAKE (formal, contractual, see: Kenneth), the BRO HUG (one handshake that collapses inward into a single back-pat — advanced; do not attempt without invitation). Each has its hour. Americans flow between them by pure instinct, the way fish do not think about water. The fist bump, I have concluded, is the haiku of the set. Minimal. Perfect. Two warriors touching armor. I returned the next day. The same young man. He remembered — his fist came up at once, with eyebrows raised, a test and a welcome in one gesture. Knuckles. Tap. "Pssshh." Both hands. Full explosion. He announced to the entire kitchen: "HE'S GOT IT NOW." I received my coffee and bowed. He bowed back, badly, with enormous heart. Cultural exchange is complete when both men are doing the other one wrong, together, on purpose.