Why only limit yourself to on punishment enema? A punishment series is more fun, assuming the person being punished can handle it safely.
Start with a magic bullet or two dissolved into a 4 quart bag filled with warm (as warm as can be tolerated) saline, and make it very soapy. I believe the recommended dose of Dr. Bronner’s is 1 capful per quart. Add 6 instead of 4 to the solution. I do this routinely and I have never had any ill effects and have even asked my GI Dr re: safety. Hang the bag high, like maybe 5 feet. Don’t prime the line and give as fast as it will flow in. Depending on how clean the punished person is, this may not be taken all in one go, nor held very long but no worries. It’s going to give plenty of cramps and prepare them for what comes next. I’d make them hold as much as they have been able to take and for however long they can hold it without a retention aid until the 4 quarts are gone. I understand the usefulness of retention aids, but there’s something humiliating and rewarding about holding your punishment enema without any help (besides, for me, once my body decides that it’s time, it’s time, and only a medical grade DBC as they use for real barium enemas in real medical settings will do the job, barely).
Rinse with warm saline.
Get a 2 quart M&M ready and make it very warm. Black Strap is best. Maybe it’s just my imagination but it’s something that I have gained plenty of experience with (for medical reasons, unfortunately, but I can still appreciate how different molasses are, and for this purpose Black Strap is what I would use). If it’s too thick for your tube, by all means, add some warm water. A little water won’t make a terrible difference on the cramps that this 2 quart explosive thing will cause. Administer as fast as possible and as high as possible (bag hung up as before and nozzle or tube as deep as it will go; after the magic bullets, in spite of the rinse, the colon will still be spasming, more likely than not). Make recipient hold until they can’t anymore. I highly recommend doing this in a tub or shower. If you feel so inclined, massage the stomach of the holder and enjoy their waves of pain. With some practice (on yourself, for I would never give anyone anything that I am not willing to take myself, albeit not at the same time as them; it’s a safety thing and a Dominant thing, you have to lead by example and you can’t nor should punish anyone in a manner that you can’t take yourself, but it’s just me) you can learn how to time the massage with the cramps and it’s going to make retention so much harder. A forced orgasm via hitachi wand or whatever works for you and for the person you are punishing could be a nice, evil touch.
Rinse with warm water.
This is a little much for most: ½ liquid glycerin and ½ very warm water. Prepare a 2 quart bag if you like but don’t count on them being able to take it all. A Higginson works great, too. Add some air for extra discomfort and for a noisy, humiliating expulsion.
If this punishment series doesn’t do what it’s supposed to do, I don’t think anything will.
Please make sure that a very thorough rinse series follows. Offer an electrolyte drink like Gatorade (zero or regular) throughout the session. Check on wellbeing of recipient and on verbal and non verbal language at all times. Safety first and this is a very rough punishment. Use a safe word! I would personally provide a great deal of aftercare, too, but that is, again, me. Play safe and enjoy!