Karen turned and faced John and her thighs touched his bed as he leaned over in her direction and kissed her pussy mound. His sister instantly stiffened up but she didn't pull away. As he lingered there kissing her mound softly and nuzzling his face in her pubic hair his sister started to relax.
"Is that precum?" Karen asked as a droplet of precum started leaking out of the slit in the head of John's dick.
"Yep, that's my precum. It's slippery, it acts like a lubricant, go ahead and feel it if you want to," John advised his attentive audience.
John returned to kissing his sister's mound. He could smell her arousal. He slipped his tongue out and pushed the tip of it between his sister's tight labials and started searched for her clitoris.
"Oh, oh what are you doing?" Karen stiffened suddenly from surprise but again she didn't pull away, "did you just lick me?"