Informal ways of calling people

[Caballero]

I guess you're right, this should be a separate topic.
What do you think of these other phrases and this video? And how do they sound in other countries?
Video

Informal ways of calling people - like mate or bro or brother
Che Most used one. Unisex. Hey, what are you doing? ¿Che qué hacés?
Negro/Negra literally means "black", but can be used for anyone. e.g. ¿Qué hacés negro?
Maestro. Can be used for someone that knows a lot or does things well
Master. Can use for male or female
Flaco/Flaca. (skinny) e.g. ¿Cómo andás, flaco?
Gordo/Gorda (fat) Common pet name among boyfriend/girlfriend Te quiero gorda.
Pibe/piba Used with teenagers and kids.
Boludo. Most used one in the last few years. Have to be careful because it actually means idot, but in the last few years it is used so much by kids and teenagers to mean something like mate. Have to be careful. The meaning depends on the intonation. If it's said in a friendly way it means hey or mate. If you stress it angrily it means idiot.

Why is che used so much on forums?
What is the meaning of Che in this context: http://www.groovesite.com.ar/foro/showthread.php?t=1935

...Che alguien tendra el plug-in de Winamp que graba la radio on-line o algo por el estilo para hacer lo mismo

Gracias

and:
http://www.zonamilitar.com.ar/foros/...el-foro-5.html

Che...nadie se avivo en el foro?