When somethinginevitably sad is about to take place and a person prepares him or herself mentally and/or physically to better handle the pain. Typically, precrying takes place before rewatching a sad movie or episode in a season.
To spend a large amount of time preparing oneself for a night out. This is the initial stage to "peacocking".
Etymology derives from the dominant beauty of a peacock's feathers. One who precocks has generally spent a large amount of time making oneself physically pretty for a night or an event.