Pulling out after sex and leaving the condom hanging out of the vagina or anus to let the partner know you are not finished with them, and in the case of an orgy, to mark which partner you were last with.

When a person isn't you're boyfriend or girlfriend, you aren't even dating them, but you keep coming back to them, and you're holding out for someone better.

Mark made on a person upon striking them with a book. The mark is usually a reddish color. Bruising may also occur as a symptom of being bookmarked.

The awful player on a hockey team that sits in between the forwards and the defense and gets no ice-time.

Derek who is someone’s current situation but isn’t the the final chapter

When you place your wang between the butt-cheeks of your bedmate. Sometimes an innocent byproduct of spooning, sometimes a not-so-subtle hint that you're in the mood, occasionally purely for a laugh.

What a potential date does when they want to keep you available, but don't want to commit to a specific date. They may ask your availability, but not commit to a date per se. You are on the back burner, so to speak.