I beg Your Pardon

I 've been going to the doctor more frequently lately due to chronically late periods, for the last few months (don't worry...I am NOT pregnant). I went to the doctor today and he kept talking about pregnancy tests and saying "I know about pregnancy tests." When I interrupted him and said I was a virgin. His eyes bulged and he said "I beg your pardon." In my mind I was thinking, "I know I beg my pardon, too."