milk the pigeon—(dated) attempt the impossible:
- “Why have you come here if only to fall into a brown study?” “I am sorry. I promised to do a favor for Miss Ravenhurst but I fear I’m only milking the pigeon.”
pigeon milk —(also: pigeon’s milk)
1. the partly-digested food with which pigeons feed their young:
- Pigeons feed the young ones from the protein-rich “pigeon milk,” a curd formed in the parent bird’s gut.
2. (dated) said of an imaginary article for which children are sent on a fool’s errand:
- Boys and novices are frequently sent on the first of April to buy pigeon’s milk.
Note: The expression does not correlate in meaning with the phrase mouse milk—(coll.) anything that delivers little payoff while requiring lots of hard work:
- When Carl said that making this stuff was mouse milk, what he meant was: it takes a hell of a lot of whatever they use to make it out of to make a little bit.