A Post cereal. Like eating gravel with milk, until it starts coagulating into a substance that you could use for spackling and caulking. Perhaps the quintessential "adult" cereal, esp. when consumed with skim milk. I call it Colon Blow, after the Saturday Night Live skit: "It would take 10,000 bowls of your regular high-fiber cereal to equal just one bowl of Colon Blow!" However, it does not reduce masturbation, as intended - unless you were to masturbate with it.

The following is from a Grape-Nuts ad circa 1907. I have no freaking idea what "Postum" is.

Try the change.
You will feel "fit as a lord" in a week's time by breakfasting on Grape-Nuts and cream, a little fruit, a soft boiled egg, some nice, crisp toast, and a cup of well-made Postum.
If you ever try this experiment, you will always bless the day you woke up. (huh??)
There's a reason why Grape-Nuts food furnishes power to body and brain. It is made of selected parts of field grains that furnish phosphate of potash in a natural state that can be assimilated by the human body. This joins with the albumen of food and forms the gray matter of the brain and nerve centres.
Feed skillfully and you can "do things." (my favorite sentence)
The greatest brain workers eat Grape-Nuts.
Ask one or two, they'll tell you.
You meat eaters who are ailing in any sort of way should take the hint.
A prominent authority says: blah blah blah
You can depend on the energy from Grape-Nuts longer than from any meal of meat.
"There's a Reason" for