Brother and Sister Peehole Temperature

I don't know whether my sister believed me, or just wanted to go along with it. Furthermore, I doubt she was really worried about having COVID-19. We've both been careful, knowing that at our age, we're relatively safe, but could infect more vulnerable people. So any way, I told her that we should take each other's temperature. Now, I've been interested in urethral play lately, so I proposed that the best way to take temperatures is to insert thermometers in each other's peeholes. She said "Sure," so I knew immediately she was onboard with it. Maybe it was because we've been self quarantining for days, and she was bored, or maybe because she was as excited as I was. I do believe it was the latter. We took our clothes off. Or, because it's more celebratory, she took my clothes off while I took hers off. I was immediately erect, and as I found out a minute later as she laid down on the bed, she was immediately wet. Now, one doesn't just jam an old-fashioned glass thermometer into one's sister's peehole. I could imagine that would be uncomfortable. So, I took considerable time noticing her inner labia by fondling them as best as I could considering how slippery they had become. Finally, I spread her labia far aport, got a good look at her little tiny peehole, and slowly introduced the thermometer. She reported that it stung a bit. When I started to pull it slowly back out, she said, "No, keep going." I pushed it in a full two inches, feeling the resistance as it passed her urinary sphincters. She started orgasming right away, with the thermometer bobbing back and forth an inch or so with her internal contractions. Next it was my turn. She got me good and hard, almost going to far to where I would have ejaculated. Then she greased up the thermometer with her pussy juice, and pushed it slowly deep into my erect dick. I came. What else could I do? The pumping just started up automatically. I was glad it was an anal thermometer, the kind with an enlarged bulb at the end because it blocked the semen in my urethra as my body was trying desperately hard to eject it. But it was locked in, and that caused my contractions to be twice as strong and last twice as long. I wasn't expecting that, but it didn't hurt a bit, and was absolutely fascinating. I was kind of afraid that the internal pressure would hurt my body, but no, all was fine. It did sting slightly when I peed for the next day or so, but otherwise it was a wonderful time for a shelter-in-place brother and sister.