死磕

死磕	sǐ kē	(coll.) to fight to the death
死	sǐ	to die / impassable / uncrossable / inflexible / rigid / extremely / damned
磕	kē	to tap / to knock (against sth hard) / to knock (mud from boots, ashes from a pipe etc)
磕	kè	variant of 嗑