It stands for Saint Mary's Drill. It cosists of one half of the team running multiple killers while the other half does fun things such as burpees. Guaranteed you will not be able to feel your legs for the next two days!
Smd is the acronym for "shake my dick." This term is used in response to people on the internet when they say attempt to sound profound when disagreeing with you but have have nothing to say besides"smh" which is the acronym for "shake my head." This term was coined after being fed up with prepubescent kids online thinking they're the shit.