The expression "G Day"

 G Day is a contraction of good day....
 Australians used this expresion to say `hello´ and `hi´.
Also, used in the constructions G´day mate ( a greeting to a friend or acquaintance) and G´day, stranger 
(ironically, to a friend not seen in some time)...

His pronunciation is : /ɡəˈdeɪ/

I am going to leave you a funny video..

 - Source: Wikipedia