Vietnam had some pretty rough smells, but the revetments where the helicopters were kept probably smelled even worse, because of those premission pisses.
I, like everybody else would try to relieve myself before a flight, but one time a hasty depature ended up with me having a full bladder that couldn't wait. This was a OH-6, no doors. I knew it probably wasn't a good idea, but I was desperate, and I didn't want to just piss in my flight suit. With all the air swirling through the cabin, I might as well had wet myself, and the pilot. It was a good thing me and that WO pilot got along pretty good, usually.
There's some primitive instint that makes us all want to eliminate everything in our body before doing smething risky. I've noticed the same thing with race drivers before a race.
I always carried a large Gatorade bottle when flying missions in the UH-60. In fact we all did, and the female crew members had those "Go Girl" Female Urination Devices so that they too could use a Gatorade bottle. When you are flying around all day, you gotta go when you gotta go...