Ticklish toes are the best! But so elusive to isolate and tickle without the lee scrunching their toes. But try this one...
You need a brush something like this and a bit of baby oil or personal lubricant (a better choice I think). As you draw the brush between her toes she won't be able to grip and "fight off" the tickling. And if her toes are really ticklish the sensation is going to be insane! Practice on your gf's adorable toes and report back to us