In theory, absolutely yes

In practice, I don't have great feelings about the consent side of touching your girlfriend without her explicit consent, especially as she and I have never met. I don't know you, I don't know if this is a surprise she would like or if this is just another guy fantasizing without his partners knowledge or understanding.

I get this question a lot and it always feels a little icky, it usually comes from guys with partners who don't enjoy or like being tickled and so the man tries to satisfy himself with fantasies of making her take it anyway.