Anon - you - Umm, I mean your friend - can either use a douche, or take the head off the shower and use the hose. Make sure the water isn't too hot..
If using the shower method, bear in mind that the force of the water can be quite strong - you don't want to tickle your tonsils via your ass...!
ALSO - very important too - insert the hose for only a few seconds, but DO REMEMBER to clench your ass cheeks and make sure you're close to the loo as you won't be able to hold it in for too long.
Don't want any messy accidents, or having to poke the poo out of the plug 'ole, lol.
You may need to re-insert a few times to ensure total cleansing.
One of my clients occasionally enjoys prostate massage, and he tells me that he eats mainly rice the day before - apparently rice is great for clearing out the pipe(s)
And no - I don't do anal either - just pretty clued up and have
the occasional colonic