Another name for Valentines Day; the holiday is similar to thanksgiving in that the few days leading up to turkey day you abstain from over eating so you can make a total glutton of yourself on the one day where nobody looks down upon such an act. On sexual Thanks giving you abstain from intercourse a few days prior so you can have a marathon sex session that rivals Sting's best efforts, may also be used for an anniversary or birthdays.
Wife: What are we doing for Valentines Day honey?
Husband: You mean sexual thanksgiving, and what do you think we are going to do? You better get ready because I'm going to knock the bottom out of you!!!