The act of having sexual intercourse with another person.
Would you takedown that chick?
Did you takedown that girl from the bar last night?
That girl is pretty hot, would you take-er-down?
A girl or guy who is by all means uglier than the average ugly. Doesn't have to be fat/skiny/etc, just plain ugly.
Phil drank so much on Friday, he ended up taking-down(See def.) a real gnar-gnar.
I wouldn't make out with that gnar-gnar if you paid me $10,000.