There is a new scam method being followed, quite often now when you do something like insurance, energy plan, etc on the telephone they waffle out a bunch of conditions and want you to respond "Yes" if you have done one of these lately you probably know what I am talking about. Anyway, the scam, someone rings you up, when you answer they are "Can you hear me?" the normal response, if you can, would be to say "Yes?!" what then has happened is that they have recorded you agreeing and they use this as proof that you have committed to a purchase, change energy/phone providors, change a plan or whatever.
So now we have to be careful saying "Yes" on the phone to avoid being the target of fraud (sigh). If someone rings you that you do not know avoid say 'Yes" or any other agreement word as you could then be hassled trying to undo whatever they were trying to trap you with.