Anal sex
Anal play has been around since very long time, precisely, oldest anal plug discovered so far is from Cina, 2000 years old, made of bronze. Anal sex is still a taboo today, even though porn and internet made it a bit more mainstream.
There are different toys dedicated to anal play, no matter the one you choose, remember it’s common practice and safe to buy toys that have a base diameter over 2.3in, to avoid to loose the toy during the play.