The speaker is doing something ordinary, washing day, when a stranger's remark drifts into earshot: trying on different minds costs nothing. The company laughs, as if it were a light, clever joke. The speaker doesn't join in. Something about the idea unsettles them, and the poem leaves us to guess why. Perhaps it sounds too easy, as though changing how you think were as simple as trying on a coat.
The ending is the surprise. Instead of arguing with the woman or explaining the worry, the speaker goes and buys a couple of lobsters. It's an odd, slightly comic response, and the poem doesn't say what it means. It might be a way of shaking off the unease with a small treat, or a turn toward something solid and physical after an airy idea. The title's play on "brain washing" ties the laundry to the mind. The mood is quiet, wry and a little uneasy, with a lightness that hides a real question underneath.