Just found that vim have a operator macro that do ROT13 transformation.

Try it on these:

How can you tell an extrovert from an
introvert at NSA? Va gur ryringbef,
gur rkgebireg ybbxf ng gur BGURE thl'f fubrf.

Vim will do this for us, have the text above in vim, then stroke follow keys:

ggVGg?

And produce:

Ubj pna lbh gryy na rkgebireg sebz na
vagebireg ng AFN? In the elevators,
the extrovert looks at the OTHER guy's shoes.

Type ggVGg? again will transform it back… Bah… stupid fun lol