Same thing applies to the whole "sex while I wear a gas mask and she has an apple stuffed in her mouth" conundrum. Initially when you first start seeing someone, you're still not quite comfortable with each other in bed. Then one night maybe a month or two into the relationship, you two will come home one after a romantic evening of dinner and dancing, and you'll be like "ok fuck it" and you'll break the gas mask out from under the bed and put it on shortly before penetration. Then your woman breathes a sigh of relief and pulls an apple out, says, "I'm going to stuff this apple in mouth while you bang the shit out of me, you big bad insane fireman" and then she crunches into the apple and holds onto the bedposts while you kill it from behind. The whole time you're breathing heavily - sounding like Darth Vader - and watching the whole scene through the greenish night vision of the gas mask goggles.