[Gay]

sdfsdf

  I'm wondering what's sdfsdf. I saw it right now, online.
 As far as I know now, the 3 characters (s,d and f) are located next to each other on a keyboard, so people might just type them quickly to fill in the subject line (or elsewhere, for instance -- a nickname sdfsdf), because they can't think (or don't want to think) of anything to write there.
 So... sdfsdf! And bye-bye!

[MSL]

 Yes. As you know, it's "a,s,d,f,g,h,j,k,l" on the keyboards . By the way there is a similar one -- CDF: cumulative distribution function.

[Xsokii]

More likely they had a stroke IMO.

[MSL]

  That was an interesting explanation.