According to Wikipedia:
unf, an onomatopoeia for sexual intercourse, possibly an acronym for Universal Noise of Fucking
Also I heard a great analogy for marriage. 50% of American marriages end in divorce...so this comedian was like, "Yeah what if you went skydiving and they said 'Its fun but about half the time the parachute doesnt open.'" It's totally like that man. Half the time the bitch cleans you out and takes "half" of your assets (which works out to be like 75% or so...because apparently a non-working woman is more fit to take care of the kids than the guy who busts his ass 8 hours a day over the course of their 18 years). The other half of the time you're locked in a monogymous relationship (which often only applies to you..if you cheat on her, you're a dirtbag. If she cheats on you, it's because you didn't fulfill her emotional needs and she had no choice in the matter). Maybe like .5% of the time you're married (so 1% of the time you don't get divorced) it doesn't make your life a living hell and actually makes it better.
I'm biased, I realize this. My dad consistently works 60 hours a week, and at the beginning of his career 80 hour weeks were down weeks for him. My mom gambled away their entire life's savings, cheated with multiple men, and then managed to get 3/4 of all his future earnings because she got custody of my brother and I, as well as the fact that she supported his career.
Marriage in America is fucking horrible, and on the off chance I do shack up, there's going to be a 2000 page long prenup.