Your signature is just the way your hand has been conditioned to spasm while holding a pen.

[SwimModSponges]

So there's that. 

[stilgar]

Yes, I know.

[Doom Metal Alchemist]

......If I write something else, then obviously my hand hasn't been "conditioned" to write my signature while I'm holding a pen.

[Seight]

Oh trust me, it does looks like a spasm. 

[BlackNoir]

My signature is me writing my name in cursive...Unless it's on a touch screen....Then it could literally be a dick if i feel like it because it's impossible to sign those even on the off chance they do provide a stylus....Which for some odd reason is rare.