The s refers oftem to a spliff, to where the term S comes from but may also be a joint or blunt. You will often hear university students say the S or S is calling in the evening, this refers to the high calling to them after a long day and it used to discreetly leave a room and inform people of a sesh. This is often used to hide the motives from a larger group or from non smokers and is primarily used in Ottawa but is also gaining popularity in other parts of Ontario specifically Peel region as well as Hamilton, Kingstown & Saint Catherine
"I gotta take this call, I'll be back."
"Is the S calling?"
"Yes."
"Guys I thinks the S is calling."
"Ahhh shit, I knew it"
"What's up with him?"
"I think the S called."