Rolled cigarettes consisting of butts either removed from the ashtray, someone else's ashtray, or the street. While considered neither healthy nor socially acceptable, they are often smoked by those with little money and a smoking habit.
Student: Oh, joy, no baccy... I guess I'll have to have an SHS.
Friend: A what?
Student: Second hand special (removes butts from ashtray)
Friend: Oh, crap, man, that's baaaad.