risk life and limb
Also, risk one's neck. Take dangerous chances, as in There he was on the roof, risking life and limb to rescue the kitten, or I don't want to risk my neck contradicting him. The first hyperbolic expression, dating from the early 1600s, doesn't make sense, since if one loses one's life one also loses the use of one's limbs. The variant, used for risky undertakings of all kinds, physical and nonphysical, presumably alludes to being hanged or beheaded. Also see stick one's neck out.