Matt's been a nuisance for criminal organizations for some time. Someone decides he needs to be humbled. They catch him unawares somehow, capture him and hold him in a torture chamber. There's mostly psychological torture though, with force-feeding him some kind of fluid that makes his stomach howl with pain and bloating, making him too sick to hold in the diarrhea, etc. Telling him how filthy and useless he is, to crap all over himself like that. Giving him painful, too big, too hot (or cold) enemas and living him plugged for hours only to make him beg to be allowed to go to the toilet. Just desperation all around. The kidnappers keep him blindfolded so his blindness is not obvious to them.
Don't forget that his senses are enhanced. The fullness, the cramps, the temperature, all the sensations and smells - make it as detailed as you want =)
Happy end is welcome but not necessary.