A butthole that has seen its share of action, thus being no longer taut. Rather, the butthole has become loose and has a larger circumference than it previously had.

Anatomically, the anal sphincter is unaffected and remains tight, while the butthole has some 'slack'.

Metaphorically, think of the butthole as a collar of a t-shirt, and a slack butthole as a 'bacon collar' due to constantly expanding and contracting.
Ben, how was that girl last night?

Gosh Brian, after she plowed my anus with a strap-on, I think I have a permanently slack butthole. So she was great.
by fgwg2 October 13, 2015
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