there's no possible way it can be executed, the antivirus finds it when your browser makes a cache copy of the gfy board on your hd, the antivirus just compares its database with the text string on the cached file. for example you can even paste the code into a jpg file with a text editor and it will be detected, but it won't be executed if you open the jpg in your browser or photoshop.
btw, don't be afraid of having that source up there, you can click here
http://www.google.com/search?q=virus+source+code and choose whatever you like, have fun!