How to test if she likes me by making her blush?

Ok ladies here is the question: if you really like a guy, what is one thing that he can do or say to you to make you blush? (other than kiss you).

Because I want to test out if this girl likes me since sometimes she blushes around me but usually she doesn't since we aren't nervous around each other since we've been good friends for a long time.
How to test if she likes me by making her blush?
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