Within every language there is typically a word used to get the attention of a person whose name you don't know. In Arabic it is Isma, in Malay it is wei and to some extent in English it is Oi! The latter two can be considered quite rude though. The Nuer in Akobo have, by far, the coolest phrase:
Now you may be asking, "Why is this so cool?". Well if you were ever much of a video game geek back in the day you may be familiar with this sound. The only example I could find of this being used in an old school game is Zangief in Street fighter II (1:20).
I've also heard this sound being attributed to Warcraft II and Im quite confident there are some other fighting games that came out of Japan that used this sound.
Talk about a warrior culture
(Or if you have database access)