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.)
If you are in it for a relationship, I’d ask them why the fuck it was any of their business. Are they loose or tight? Are they dry? Do they stink? Ask any reversed gential-related questions to put some perspective on it. And consider moving on to someone else. I guess if you’ve been together a long time and more personal with each other but not having sex, it can be borderline ok from a curiosity standpoint, but if they are shallow enough to have that matter to them, better to just be honest and potentially done with them.
If you guys are just in it to bang, then give any witty response you want. If they double down after that, ask if they are serious or if it matters to them. If it does, give an honest answer. Maybe they are shallow enough to care in which case you are dodging a bullet.