to relax - via sexual intercourse, the use of a dildo, fist, or other object - an anus to the point where it will remain open, at least for a short while, when the penis or dildo is removed. This is a desirable goal in certain kinds of fetishist anal play, e.g. the open anus is considered visually exciting, or it can be urinated in, used during scat play, etc. Sometimes "medical" devices, such as a speculum, are used to keep the anus open for similar purposes.
Next time you want a milk shake, go ask your wife to open up a gape hole! :)
Person 1: Oh my god!
Person 2: Whats wrong?
Person 1: Wubby won’t show gape. I swear to god if he doesn’t I will clime through his window and fuck his ass.
Person 2: ...