in my article about lube here.
2.
If you have a chance, prep for anal sex: Our anal canal is
a passageway for things to head out, things are rarely stored
there without us being aware of it. But for those of us that
want to make sure we’re nice and clean, here are some tips.
Wear a condom. Non-tested partners should be wearing
condoms anyway to protect each other from transmitting
STDs. The anal canal’s surface is fragile and can micro-tear
easily (see the steps about lube to help prevent this), so it’s
especially wise to use condoms during anal sex. Condoms
have the added bonus of easy clean-up if the butt isn’t as
empty as you’d like it to be.
Eat foods that day that will be nice to your body (meat and
potatoes, no Indian curries!). Having a nice, solid, bowel
movement before sex is the most natural way to be clean.
Clean yourself out with warm water. There are many
methods: using your finger while in the shower to “rinse out”
the area; using an anal douche to clean out the first 10 inches
or so of your goods; or by rinsing out using a get-up attached
to your shower head (there's even a “travel version”). Many
people want to know if an enema is necessary before anal sex;
all of my sources (including former registered nurse Nina
Hartley) believe enemas to be too invasive for regular anal
play. Enemas clean out much more than is necessary; you
only need to clean out the bottom 10 inches or so of your
canal for good, clean, anal play.
A quick note about what happens when you aren't as clean as
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