Years ago with my first TG-GF I had sucked her to one orgasm and was working on her next, she was pre-op at the time. I came up for air and asked her how many she could go for. After a bit of conversation she gave permission for me to bind her and give her as many orgasms as I could, as in Forced Orgasms. We lost count after ten but kept going until she was exhausted and I too was too tired to keep sucking her. She told me that she had never had so many orgasms in a single day let alone back to back in a single session. That's still a pleasant memory.