- call of nature
- the need to urinate or defecateThe visit demanded by your bodily functions:I was probably off the road, behind the bush, answering a call of nature. (Follett, 1978)'When nature calls, heh, heh, hen,' he'd said... and made his way out into the trees. (M. Thomas, 1980)
How not to say what you mean: A dictionary of euphemisms. R. W. Holder. 2014.