The term used when one would like to announce to those around them that they are leaving to smoke a joint, particularly when in the presence of authority figures.
(In front of the proctor) Hey guys, anyone up for a nature walk?
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.