My best friend just told me she is masturbating what should i say back plz answer?

We r both 14 im a boy and she is a girl i simply just texted her hey sis what ya doing and she just replied masturbating wbu so what should i say to that is she joking around or telling the truth plz give sensibly answers btw we call eachother sis and bro so don't point that out plz help