Masturbating a woman or girl to orgasm. This takes its name from the "flicking" motion of the middle finger when you are using a wheelmouse and trying to scroll down through a lot of text. In masturbation the action is almost exactly the same, except that the mouse wheel is replaced by your lucky lady's clit.
Also, I've noticed that the sound produced is completely different.
A similar computer/sex term is "double clicking on the mouse" which also means female masturbation.
HMB (who is male): So, AC, what did you do all day today?
AC (who is female): You would not believe. I found a kick-ass .zip of photochopped fake Johnny Depp
porn. It was a really big file, too. I had to spend almost two hours rolling the mouse wheel just to get through it.
HMB: Dear me. Airing the orchid?
AC: You bet. I got my daily musical practice of playing the upside down piano.
HMB: Feeding oats to the pony?
AC: Tickling the toothless gibbon.
HMB: Typing in the gussets.
AC: Paddling the pink canoe until it leaks.
HMB: Finger painting the ham sandwich.
AC: Stirring the mixing bowl.
HMB: Petting the cat.
AC: Fingering the bald suspect.
HMB: ... So, um, can I borrow that .zip file? ... For, erm, personal reasons...