have you tested your what?

OK - here's a priceless situation

Unidentified mid 60's white haired male comes into the kitchen at mum and dad's while i was staying there for a couple of days. 5pm. My sister is also there and like me, she is kicking back in an armchair with a book. (my kids were out in the garden with my mum).
Q: would you girls like a drink?
both: no thanks.
Q (again): would you girls like a drink?
both: no thanks
Q(with head poked around the corner from the kitchen so as to make eye contact): would you girls like a drink?
both: no thanks
Q(from me this time): have you had your hearing checked lately?
A(incredulous): have I had my urine checked lately?!