Used when a male sees a very attractive women. The male would say 'nice' but was used so often the 'ce' of nice was eventually stretched out, making the the sound of a snake (Sssssss). So in its case, the 'Sssssss' is known for an undercover "nice" so no girl looks at the male like a creep.
Dude, look at that girl, Sssssss.
by Citizens Bank (Creators) February 18, 2010