modal particle indicating that sth is obvious / particle indicating a pause for emphasis
嘛
=
口
+
麻
:
Mahatma Gandhi (m) retreated to the top of the ashram (a5) to start another hunger strike. Soon the 喇嘛 climbs to the top as well using a hemp (麻) rope, hands him a mandarin (口) and asks him what the hell he is doing (干嘛).