[setrofim_]

That's a lot to put on a sticker -- people aren't going to read that. Maybe something a bit snappier, e.g. "Freelance coder: available for gigs" or something.

I would question, however, whether putting a sticker of any kind is gonna help you score gigs. I mean, if you were looking for a coder, would you really approach some random guy/gal in a coffee shop based solely on a sticker on their laptop and knowing nothing else about them?

Maybe having a sticker with a link to your github, as suggested by others, would be more useful (if your user id is memorable).

[jiggy2011]

Depends what you are going for, unless you are looking for people who are already reasonably tech savvy your potential customers might not know that github is a thing.

I full sentence briefly explaining what you do, and more importantly giving people permission to interrupt you would stand out more than just some random sticker.

[pizza]

It's more than usual, but most people don't stop reading small bits of text mid-sentence. Plus, serendipity is a wonderful thing.