I posted on this more than 3 years ago. It's great this topic is still alive. Because the enema bag was always hanging from the shower head, it was pretty obvious when it had been used. It also made it possible to use it without drawing any undesirable attention. If mom or grandma asked who used it, there was always the excuse that it fell down in the shower. I suppose that they were suspicious however.
As kids, we made a game of guessing who got an enema when it was obvious it had been used. If nobody had recently showered, the droplets of water inside and dangling from the nozzle were pretty telling. Baths were most common and I was the one who usually showered. This allowed me unfettered access to the enema bag. My loud expulsions afterward were likely a dead giveaway but I didn't realize it until quite later.
If us kids had been locked out or shooed away to grandma's place next door, it was pretty well assured that the enema bag would be wet afterward. We never could get a total handle as to whether it had been used for an enema or for douching. My mom was so adept at enema administration that it was a safe assumption that she or dad had been on the receiving end.
Mom wasn't shy when it came to discussing enemas. She was often consulted by relatives or friends and had even lent the enema bag to my paternal grandparents for a pre-procedure cleansing. On one occasion we had a family event and when dessert was offered, my mom couldn't resist. She had eaten only clear liquids for dinner because she had an early test that required a bowel prep.
I'll never forget the discussion that followed her indulgence. The outcome was that she would just have to take a couple of extra enemas for her prep. We kids snickered and joked about that for a long time thereafter.
I also remember my uncle telling my grandpa about getting an erection while receiving an enema and shave prior to a hospital procedure. He said that the nurse flicked his penis and the erection immediately disappeared. Thank goodness the nurse didn't slap me down like that when I had a similar response to an enema in the hospital.