What should I response in that situation?

[JuliaS83]

First of all, I hope you don't mind my terrible English, and I will try my best to make it as clear as possible.

It's not a story of mine. It's of my friend.

He's flirting a girl in his class and she seems like him, too.

But one day, when a boy in the class made a comment about them "you seem quite cozy with each other, huh", the girl replied (in a joking tone) "No, he's just my toy".

My friend didn't know what to say and he just smiled.

What do you think my friend should do or say at that situation? And do you have any idea about what the girl thinks about my friend? She's just joking, or she really wanted to make my friend got that she didn't take this relationship serious (in a joking tone just in order not to hurt him)?

[shh!]

It's hard to know what she is thinking. It is awkward when an outside party makes comments about potential relationships, and the girl may have just been embarrassed and responded in a way to distract attention.

If your friend is interested in this girl, he will need to be more direct to see if she reciprocates interest.

[JuliaS83]

Thank you for your advice, I will tell my friend to do so ^_^. .