From the book One Answer to Cancer by Dr. William Donald Kelley (2010) page 38, via alternative-doctor.com:
CLEANSING THE COLON
The Coffee Enema
A high retention enema, using coffee, should be taken to aid in the elimination of toxic waste material from the body. The coffee enema should be taken daily for as long as one is on Metabolic Medicine’s Cancer Cure Program. After 35 years, Dr. Kelley still takes his daily enema.