Thinking about DD certainly does, even when we're apart. Sometimes thinking of my two older, weaned boys makes them let down (mommy response!). But also when something makes me laugh, often it'll let down. Laughing at something my students say and it letting down is the weirdest thing. I guess it's a pleasure response, laughter = pleasure just like nursing does? It's happened once or twice during/before sex, too. Just wondered if anyone else had let-down when not nursing, for odd reasons!