The initial idioms of the letter S

sit up	sit up and take notice
sit up with	sit upon
sit well with	sit with
sitch	sitcom
sit	sit a spell
sitting on a gold mine	sitting on a powder keg
sitting pretty	sitting
in situ	situation
six	six feet under
six of one, half a dozen of the other	six of one and half a dozen of the other
six of the best	six ways from Sunday
six ways to Sunday	six-bits
sixer	six-pack
sixth sense	sixty
sixty-four-dollar question	sixty-nine