It’s always the quiet ones.

Jurors in the Nxivm trial on Friday watched an eyebrow-raising video of the upstate home leased by the alleged sex cult’s bookkeeper — which showed the phrases “I suck big hard d-ck!” and “Slap my heinie” spelled out in colorful magnet letters on the fridge.

The unit rented by accountant Kathy Russell also featured an adoring photo of Nxivm leader Keith Raniere — who is on trial for allegedly running a twisted master-slave group within Nxivm called DOS — pinned to a bulletin board, and a tripod set up next to a bed in the Clifton Park abode.

Her landlady, who took the video, testified that she was surprised to find the ”juvenile” words on the fridge — which also included “boner” and “p—y” — as Russell hadn’t struck her that way.

But the 62-year-old is apparently not as straight-laced as her job title might suggest — two other Nxivm members, 42-year-old Lauren Salzman and a 33-year-old named Daniela, have already testified about having threesomes with the number cruncher and Raniere.

Landlady Sheila Jelonek said she once encountered another Daniela — Raniere’s top sidekick Daniela Padilla Bergeron — in the home, and the woman told her she was housesitting.

Jurors previously heard how Padilla — an alleged “slave” in DOS — purchased $900 in kinky sex toys in 2017.

Jelonek said Russell would meet her once a year in an area Starbucks to pay her rent on the property — with cash stuffed inside a paper bag.

It wasn’t immediately clear where prosecutors were headed with Jelonek’s testimony, though lawyers for Russell insist she only leased the property and didn’t live there.

Russell has already pleaded guilty to visa fraud in the case, admitting she presented phony documents to the Mexican consulate to bring a Nxivm member to the US.

Meanwhile, Nxivm’s tax preparer James Loperfido also testified Friday, saying the organization was a “difficult client” that made him take a five-day course in its philosophy before he started.

Loperfido recounted that Nxivm once screened a video “by a fellow who believed that taxes were unconstitutional” during “Vanguard Week” — an annual celebration of Raniere’s birthday.

The tax assessor said he asked if he could address the audience after the film to counter the “slant,” but was shut down.