Just read a fascinating article by Evan Zimroth on the Sex Diaries of John Maynard Keynes, in which there is much entertaining speculation on the code used by Keynes in one of the volumes (specifically, the meaning of the letters C, A and W.)
One of the suggestions for C is copulation, and I found this interesting:
In 1920s London the word did not necessarily always mean sexual intercourse of any variety (as we use it today) but could suggest only a kiss on the cheek (I beg your pardon, not that cheek) or a quick squeeze. In fact any flirtation beyond mere suggestive banter could come under the heading of “cop.”
Turning to OED I found that it marks modern usage of the verb as chiefly zoological. No indication is given of the sense above. Any support for this elsewhere?
3. intr. To unite in sexual congress. (Now chiefly a term of Zoology.)