Gaining

can I ask, if exist some weight gain PC software, where I can morph my GF?

Try pixlr.com if you don't have photoshop. It's not as good as photoshop but it has a lot of the same basic features plus it's free and you don't have to sign up to use it!

This is just for fun:

makeovr.com/weightmirror/

Doesn't really allow you to morph yourself really fat though

try AnmanieSMp

for morphing and deforming

www.portablefreeware.com/