going to the toilet (woman's euphemism); relieving oneself
A playful, euphemistic expression used by or about women, originally from hiking slang. The literal meaning is 'flower picking'.
I'm just going to go pick some flowers (use the toilet).
During the mountain climb, she said 'flower picking' and headed for the bushes.
From お (honorific prefix) + 花 (flower) + 摘み (picking). Originally hiking slang, likening a woman's discreet trip to relieve herself outdoors to picking flowers.