It had just (straight and directly) implied tickling, but I'll wish for it anyways. Years ago, I remember stumbling upon a Deviantart account which included a 3D art series about two sisters who are held chained against the wall of a medieval style torture chamber for unclear reasons. The descriptions told story of the sisters with a comedic tone, there were there to be tortured but they constantly kept bickering and trying to get each other into bigger trouble just out of spite and overall seemed to consider the whole imprisonment and torture thing just a major inconvenience. It had one part where one of the sisters "accidentally" slipped how her sister can't stand being tickled which resulted into the sister in question freaking out, and - after some banter between the sisters and the guard - being dragged away for several days of tickling in the special tickle torture chamber of the dungeons. The other sister was happy that she would get few days of peace and quiet now.
Does anyone else recall seeing such thing? I can't find it from the DA for the death of me and would not be surprised if the artist has deactivated.
In another installment of the same series that I remember the sisters suddenly realize that their mother has also been brought in and chained between them, and she naturally starts motherly nagging about the circumstances of the girls. Then, one of the girls wakes up and realizes it was all just a dream, and tells about it to her sisters who shudders and comments that having to stand mom there too would be true torture.