That thing where they run their finger along piano keys

[LisaJohnsonsFacebookMole]

When pianists (and I) run a finger along several keys at once or even the full doodah, is that actually written in the music? Can it even be shown in the music or is it simply a bit of added flair? Or, in my case, childish novelty at being in front of a piano

Yes, it's called a glissando, and it's often represented by a wavy line between two notes on sheet music :-)

I knew a MNer would know! Thank you