People are a lot like dogs. They feel more comfortable in groups,
don't respect you if you love them too much and enjoy heavy petting
unless they've been abused in the past.
The only
real difference is dogs show aggression through biting while humans
start addiction rumors or put your never-meant-to-see-the-light-of-day
hand job video on YouTube.
Frequently employed by people with class and children, euphemisms allow you to say just about anything in public without seeming inappropriate. Panties and genitals can be mentioned by calling them 'unmentionables' and 'number two' can practically be screamed across restaurants.
Don't feel trapped by already established euphemisms - feel free to be creative. Though nonsensical, saying you spent the night 'walking the dog' will get your point across if you speak out of the side of your mouth or use a subtle gesture.
Be aware of how much information you're giving away, though. Just because calling it Montezuma's revenge or saying you got to third base isn't impolite, your audience is still going to visually picture you suffering on the toilet or engaging in heavy petting.