Just like when you harvest an animal out of season, only you take her (or his) behind out of session.
Karen and I were having drunken sex, but during it she passed out, so I turned her over and continued the session poached colon.
Pressing the penis' tip firmly to your girlfriend's anus hole, unbeknownst to her while she's sleeping; slowly milking out a hot load of semen and ejaculating the whole shot directly into her butt without waking her up.
After me and Wendy had had a few drinks and some sex, she decided to stay the night over, so while she was sleeping I cuddled up tightly to her backdoor and fed her some communist porridge.