'扔手榴弹' literally means 'to throw a hand grenade' — a compound verb formed by the action verb 扔 (rēng, 'to throw') and the noun 手榴弹 (shǒuliúdàn, 'grenade', composed of 手 'hand', 榴 'pomegranate' — referring to the grenade’s shape — and 弹 'projectile' or 'bullet'). It describes the physical act of hurling a fragmentation or concussion grenade, typically in combat, training, or historical/military contexts.

This phrase is not used in daily civilian life and carries strong military, tactical, or historical connotations. It appears frequently in war films, news reports about armed conflicts, military drills, or historical accounts. While grammatically simple (V + O), it is highly context-specific and rarely appears in metaphorical or figurative usage — unlike English expressions such as 'drop a bombshell', which is idiomatic and nonliteral. Learners should avoid using it casually or outside appropriate domains.