Stick your finger in her asshole.

My body shudders slightly, my breathing is irregular, and my tight little anus twitches in response to your tongue, slowly circling around and across my anus. You flick your moist tongue, depositing your saliva on my hole as lubricant. I don't realize what you're about to do until after you've slobbered on the tip of your index finger and started pushing it into my butt.

There's a little resistance sliding into me, but not enough to keep your well lubricated finger out of my wet butthole. I suddenly realize there's a finger in me instead of a tongue when the first knuckle slips into my hole. The second knuckle is pressing it's way into me by the time I pull away. I rock my hips forward, slipping my butt off of your finger, and look back at you.

"Whoa, buddy. I now where this is leading, and I'm going to stop you right there. Sorry, but I'm not really a huge fan of getting ass fucked."