My bf wants to do anal and I said yes, but Ik u need to clean ‘the whole’ obviously but how do you do it?

Like I don’t want to buy a douche bc Im 17 and would feel awkward and judged buying it.

Like water & soap won’t just work surely? Like that won’t clean it all out from inside..?

So are there any at home ways I could clean it properly that will definitely work

And tips? Or things uve done before to clean it?????