gee, dody, the idiom 'what up?' is so common, your post caught me off guard.

Yes, 'what's up? (wassup?)' does mean 'what is happening?'--

because here, people get up to stuff.. (she's up to no good, or those kids are being awful quite back there.. go check on them and see what they are up to.-might be said by parents..
So to be up to , is to be doing stuff, (and if you feel ill, you might not be up to going out, or to school--the negitive uses the same idiom.)

Wassup? logically follows.

the Beatles use the expression 'let it be' --
my irish parents used to use the expression (and i do, too) leave me be.- to mean don't bother me. Most american don't use the the verb to be that way. they understand the beatle's song, but 'let it be' (accept it as is) is not a commonly used idiom here in US..not even with the exposure of the song.

since my parents use 'what are you up to now?' to ask what was i doing at the present time, i never thought the expression to be anything particularly american. Wassup? is just a short version of my parents question!


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