Getting adequately cleaned out for anal?

Sorry for the sort of gross post, but I figured y'all were probably the right people to ask.

I notice that when I'm prepping myself for anal play, there's usually a bit left that's hard to get out. I eat well and hydrate and all that, but even if I sit on the toilet for a good while, there's usually a tiny bit more left (I only notice when I get in the shower to scrub and do a finger check).

I can think of gross ways to finish the job very expeditiously, but I was hoping y'all could advise a more pleasant method.