Klasky Casupo is the animation studio that made some of the formative shows on Nickelodeon in the early 1990's and 2000's, such as Wild Thornberrys, Aaahh!!! Real Monsters, Rocket Power, and As Told by Ginger. Their biggest in-house series by far being Rugrats, a cartoon about the daily adventures a cast of babies get into. With the premise being focused around infants, adult situations never got much of a spotlight. This leaves a door wide open for the studio artists to take "creative liberties" on their off time. That's exactly what happened in 1998 at Klasky Casupo.
The only page available from the board (until further notice) is the third one. The first two pages (reportedly) start with Angelica ordering Tommy around to get her some juice. Tommy goes and gets some but adds drain cleaner to the drink. This is where the existing page begins, with Tommy bringing the poisoned juice to Angelica (note the diabolical face Tommy is making in panel 2). Tommy's mother, Didi, comes in and gets after him for having juice. His father, Stu, coming in, beats Didi, then threatens Tommy, causing him to convulse and drop "malt balls," (likely a reference to the episode, "Radio Daze" (S4E5A), where Tommy and the gang try to retrieve malted milk balls.) Stu then begin to suggest that he has been sexually assaulting Angelica (his niece). Stu begins to swig the poisoned juice. The rest of the board was graphic sexual intercourse between Stu and Angelica. The storyboard got trashed after an employee from The Wild Thornberrys saw it.
Steve Ressel, a contributing artist to the board, explained the inception of the jam and described the rest/beginning in a now defunct LiveJournal blog post:
"A Storyboard Jam isn't common on shows that allow people to get out frustrations in the actual work, but on cutie kid shows, everyone draws naked women going bonkers on giant cocks in their spare time. Inevitably, through loathing of the project, they start a storyboard jam where a continuous story evolves from artist to artist as they hand around the papers. Everyone gets a turn to do their worst with the characters. At Klasky, on Rugrats, they started this Jam in 1998 I think. The first page had Angelica being a bitch to Tommy, so Tommy gets her a drink in the kitchen and puts in dog food and draino, then toddles back to Angelica. This is where the story should have heated up, but I saw someone was intervening. I found this lone page yesterday and can't find the rest. When the Jam was handed to me I disgustedly pushed it away, and after seeing it unattended on another artist's desk for 2 days I had the idea to step up the lameness a notch by having Stu come in and be utterly abusive to everyone. The artists who saw my treatment of the characters after their refined, cultured story were getting pissed...I began the next page (I was on a roll, most people did 3 or 4 panels and I was doing 12 or so in a fervor of home filth) with a close up of Stu's crotch (on model) and then a cut away showing his entire pelvis is in fact two tight and well rounded testicles with a tiny cock dangling from above. Lightening was bouncing around and words appeared saying 'BALLS OF THUNDER!', or something to that effect. After that, the next artists really took it to it's low as Angelica's hands came in to stroke Stu's balls and then incest sex scenes flew all over the pages. I was disgusted, even, when I saw what had become of the comic. Someone was taking the things between buildings, to dump it on the Thornberry crew when an executive snooty-draws producer saw it, was disturbed, and confiscated the jam... and thus it ended."
There are probably dozens, if not hundreds (even thousands), of storyboards like this sitting in a studio archive or a former employee's garage. It's only a matter of time until they get out.