两肋插刀

liǎng lèi chā dāo

lit. knifes piercing both sides (idiom)

fig. to attach a great importance to friendship, up to the point of being able to sacrifice oneself for it

liǎng

two

lèi

rib

chā

to insert

dāo

knife; blade; single-edged sword; cutlass (CL:把[ba3])