Ive done marshmallows plenty of times, the giant ones to. definitely need a moment of gentle relaxing and stimulating with fingers 1st but after a bit of time things are open for business. a bit of water is all the lube mallows need, you can suck on them for a bit to give that, tho i suggest you have some gatorade handy. your going to be getting quite a sugar rush and you ought to be well hydrated or your going to feel sick. they become extremely slippery when wet, and if your stimulated and your back door is relaxed like waiting for a poo, they will pop right in. they wont be staying in for long tho. i can manage 4-5 of the giant ones comfortably, (and ive learned not to overdo it unless i want a bad case of gas and cramps for hours,) than on goes a diaper and im off for a 15-20 min bike ride.by about 20 mins there going to start pushing out pretty hard, the sugars irritate the bowels and make things go into hyper active. if you haven't had a dump in a while it probably just makes it stronger, everything comes down and settles in the rectum, and the rectum starts drooling mucus. this is the other reason to be well hydrated, your body is going to squirt out a good bit of fluids down here. all in all it can be very pleasant if you are well prepared for it, rather nasty if your not. the major key is hydration,and of course knowing how to relax and work with your anus to accept objects is a given. i wasn't sure if i always had a bit of IBS to begin with or not, but for me the urge does become quite uncontrollable. by about the 20 min mark ill be leaking uncontrollably tho not actively pushing. but inserting a firm object, like a plug, pushes things over the line, the full solid feeling becomes too intense and the urge to push down is irresistible. if you enjoy this sort of thing have at it. just remember to wait at least 15 mins so that the mallows have softened to the point where if they come shoving past the object inserted, they will probably be so soft that no harm can be done. if you want continued play after the 1st load is ejected (and you will probably be pretty tired by now) i do not recommend using a plug behind more freshly inserted mallows, they may be too firm and will immediately be ejected, possibly causing a tear if several are forced out around an object.. they may be soft but there still big and not completely mushed up like the ones you had held for 15+ mins at body temperature.
again i can only speak from experience, but for me this is the most powerful stimulant laxative i have come across yet. (and ive tried a few)
the urge to expel can not be resisted if you use enough of these at once. you will push it out weather you try to or not. ive been looking for something that can generate this feeling, and here ive found it in an ordinary foodstuff.
a good enema kit standing by for cleanup afterwards is also nice, flushing the remaining sugars and starches out of there so you can settle back down to normal more quickly.
if you have heart conditions, diabetes or anything that would make you averse to a powerful sugar rush this is not for you. and even than you may feel like a kid thats eaten too much halloween candy for a while.