This reads like a joke question, I know, but I actually mean it.
Are you supposed to answer this sort of suggestive question with honesty? Or is this generally meant to be answered in coy and or affirmation? Because I don’t want to ruin the mood but I also don’t want to unwittingly spoil her expectations. (FYI, I’m average sized.)
never ask a woman her age or weight.
never ask a man his penis size.
if someone asks you how big you are tell them, “big enough to ruin your night”. could be both ways and still enticing enough to continue flirting.
if she continues to ask, tell her “you could find out yourself if you’re inclined.” then offer to go somewhere.