I thought " fornicate" Might work, but that seemed too judgy.

本以为用“私通”可能没事，但这个词带有评判。

Andrew, Danielle, daddy's going to fornicate for us! -Just keep your voice down.

Andrew，Danielle，爸爸们面前通奸了。-小声一点。

A bunch of booze-drenched hill people just sitting around in their underwear and-and chasing rats and fornicating in the stairwell.

一个全身酒、穿着内裤乱跑，一个追耗子，还有一个楼梯口就搞起来。