Girl. I bet you look clean and fantastic, and I guarantee your SO would love to fix that and get you all messy ;). Though easier said than done, I bet your SO thinks you look fantastic and isn't turned off by the stutter. Sex is an intimate moment and it's important to laugh if something's funny. Sure, you might try to say something sexy and stutter which makes something sound odd, but it's whatever, just laugh at it :). Sex is fun and messy. Laugh if you need to, but I can guarantee your SO digs you.