The initial idioms of the letter B

be skating on thin ice	be skin and bone
be sleeping at the switch	be sleeping at the wheel
be sleeping with the fishes	be sloshed to the gills
be slow off the mark	be slow on the uptake
be smashed to smithereens	be snatched from the jaws of death
be snowed under	be too
be soaked to the skin	be soft on
be sold a pup	be (as) solid as a rock
be (someone's) strong suit	be (someone's) funeral
be (someone's) huckleberry	be sorry
be (as) sound as a dollar	be spick and span
be spitting in the wind	be spoiled for choice
be spoiling for	be spoiling for a fight
be spoilt for choice	be spoon-fed
be spot on	be squashed (in) like sardines