She opens the door right back up.

After no more than 3 seconds she swings the door back open her face alight and says "OMG BRO YOUR DICK IS A FUCKING MONSTER!" In less than a second she is on her knees in front of you before you can even react. Getting hands on with your dick, getting just an eye full of it. inspecting it from tip to base with her eyes, getting her hands around it, and giving your balls a slight lift to feel the weight. She was acting like a kid in a candy store with your dick, to which you respond with "Sis the fuck, let go of me!" The new bimbo version of your sister, half naked looks up at you with a vigor and energy untold and goes "Oh come on bro, this is the biggest freaking dick I have ever seen how could you not expect me to be impressed, you make horses look small!?"