The simple answer is "fast". But truth be told, there is some skill involved and there are also some definite no-no's . If TMI (too much info) can make you squeemish, beware because here's the real scoop on poop.
Very few people enjoy pooping in the cold. It’s not the relaxing daily ritual that it is back home. In the polar regions pooping is all business. Rule number one is avoid the wind. Go behind a block of ice or dig yourself a wall. Consider using your vestibule just prior to taking down your tent (or not, depending on your group…). If all else fails and you have to go in the open, face the wind so that your bum is protected. There’s nothing worse than freezing your sphinct- ok…you get the idea.
Toilet paper? You bet. Some people swear by the “snow ball swipe”, but that is WAY to hard core for the general population. Pack yourself some toilet paper (TP) or paper towel (less likely to tear). One sheet a day of paper towel should be fine. It’s easy to burn through the TP by making a new wad each time you wipe. To prolong your TP re-use your wad by covering it with a new layer of clean TP each time you wipe. This way the wad gets bigger and bigger, and you use minimal TP.
Almost everyone who has pooped enough in the cold will tell you that occasionally you make a mess. Outer clothing is bulky, hoods fall over your eyes, and ski boots sometimes get in the way. If, rather, WHEN this happens to you, don’t panic. Simply leave the poop-stained article outside until it freezes and then scrape it off. Don’t spend time exposing your hands to the cold or using too much of your precious water trying to clean up. And don’t be embarrassed. Consider it a battle scar and a good story for your pals back home.
Finally, think about your impact. Some areas (like Antarctica) require you to pack out your poops. Others don’t, but if there is any chance that others will be following in your footsteps you should at the very least cover your poop. Toilet paper can be burned or packed out. Talk with your guides/group about how to handle your trash and ways you can minimize your impact.
Your time alone while pooping may be the only time you spend alone all day. If possible, take a deep breath, look up and enjoy the view. Relish the fact that you are in one of the most incredible places on the planet! Smile. Now… back to business! Quick, pull up those pants and put your fingers back in their mitts before you have REAL troubles!