rear guard 

A devise that prevents any penetration from behind

I almost got raped but thankfully I had a rear guard

rear guard by Benis man October 3, 2021

rearguardless 

When someone is very open to anal intercourse.

Hey Jack, you’re into anal go say hi to Jill is hear she’s rearguardless.

rearguardless by Blair&Zac January 27, 2019