This is my first LoRA so it might not be exactly as it should be.
Since I found no good SDXL tape gag (at least for the checkpoints I use) I trained this on a set of 150+ images (most made by AI) of tape gags.
It is supposed to draw a strip of tape over the mouth.

The training set contained both realistic and graphic novel images, hoping that the gag will work in most settings.
The word I used was tapegag, but I guess if you also use gag, gagged, tape gag, it should help.
Anyway, try it and I'll see for a better version in the future.