Build a fort 

Get under the blankets and have one person on top while having sex

U should come over so we can build a fort.

Build a fort by Mrsjohnson3 April 6, 2018

got so much wood i could build me a fort

I have so many cars I could "build a fort"

I got so much wood I could build me a fort

got so much wood i could build me a fort by Libbie V June 20, 2015

just built a tree fort 

An inconspicuous term used to notify friends that you had intercourse for a long period of time. That you figuratively just "camped-out" at her "site".

(aka= was building a tree fort)

GUY1: "So what did you do last weekend?"
GUY2: "well, not much. . . just built a tree fort"

just built a tree fort by Tomchew87 October 2, 2014