Why is my ex friend randomly asking me to do something?

[Anonymous]

I was friends with this girl but she got annoying so I haven't talked to her in weeks. Today she just randomly texted me her brother's phone number and was like "it would mean a lot if you can say happy birthday". I literally don't know her brother and never met him before. Now I'm in an awkward situation because I don't really want to do it in order to distance myself from her but I also feel bad.

[baserunner611]

She test you, see how much you like her.
What you would do will not do for her