A couple years back we hosted our extended family over for Christmas. My sister walked in on me masturbating in my bedroom (I have a pretty major addiction, and get off multiple times a day regardless of circumstance), she was 22 at the time. I panicked immediately, but instead of freaking out, she giggled and stayed, closing the door behind her. I didn’t know what to think, so I just stood there frozen with my hand on my dick. She looked at me for a second, and then said “Well go on!”
I hesitated, not really believing what the fuck was going on, and she sighed, seeming almost annoyed and then walked over to me. “like this?”, she said as if coaching me, as she reached down and moved my hand up and down along my cock. I blushed beet red, and then slowly started doing as instructed. I held her gaze, unsure of what to think, but she just looked back at me with this amused twinkle in her eye, and I started to get really turned on. As I got me into, she seemed pleased, and came close to me again and started jerking me with her own hands. She surprised me with her skill as she played with my balls with one hand while stroking me with the other.