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1.
rmx
Otherwise known as the "remix"
Ludacris - Put your money (rmx)
by tys March 05, 2005
 
2.
RMX
RMX is Twitter shorthand for remix.

It's a retweet (RT) where you do a mashup on the original tweet adding your own opinions.

The original twitterer @aaamplo writes:

watching Wolverine trailer http:\\fakelink

So a regular RT would be:

RT @aaamplo: watching Wolverine trailer http:\\fakelink

But an RMX would be like:

RMX @aaamplo: Wolverine trailer http:\\fakelink sux vs. Origins http:\\fakelink2
OMG @burdturtle totally pwned @gruenwink with his snarky RMX ! What a #failsave
by RMXfail May 05, 2009