Looking for a recipe that gets more irritating the longer its held

I'm somewhat into self bondage and enemas provide a stimulus that I can't control while being bound.

I've tried many different types of enemas: cold (body warms it making it less irritating), soap (different varieties but again as time progresses, the bowels seem to become used to it), large volume (ditto). I've tried lemon, M&M. I've also tried the biscodal tablets (crushed and uncrushed). I refuse to do the soda and vinegar thing to cause gas as that sounds incredibly dangerous to me. I even tried to create capsules of liquid soap that I could insert but they either wouldn't work or wouldn't go in 😢

My goal is to slowly have my body reject it over time. The longer I waited to expel, the more terrible the cramps would get, all within the confines of the bondage I've sealed myself within.

Any suggestions?

Amber