Drop Anchor Meaning

Example : 2005, John Illig, Pacific Dream, ISBN 9781932762372, p. 204 (Google preview):  Junkyard Dog always stopped for lengthy bathroom breaks by announcing his intentions in advance, using a different euphemism every time, saying, to name a few, "I have to: drop anchor... do some paperwork... lay some foundation... pinch a loaf... lighten my load...."2011, Andy Weir, The Martian, ISBN 9780553418026, ch. 9, p. 95:  And if you think things are bad after opening the piss box, imagine the smell after I drop anchor.2014 Feb. 24, Ashley Burns, "A Company Will Soon Offer A VIP Public Restroom In New York City For $8 A Plop," UPROXX Web Culture (retrieved 26 July 2015):  POSH is the perfect alternative to . . . stopping in a filthy, germ-infested public restroom to drop anchor. . . . Instead, the POSH Stow and Go offers people a private, clean bathroom experience.