I used to date a lady that would, during foreplay, comment that I really needed to ejaculate bad. Not the exact wording used, but it was still a little weird. Not weird enough to break my stride, because it was true enough, and with her working the pieces parts that would lead up such an event, it could have been extremely weird, and I would have been okay with it.
This goes on for months before she finally said, "I don't know how it fills up so fast, we just did it an hour ago.", during a rather busy weekend that included a great deal of ejaculation. I asked her what was filling up so fast. She said "your balls, they just get so big when they're full."
This lovely, wonderful lady had made it into her early thirties under the impression that all of the semen was produced and stored in the testicles, filling them up continuously. She was also under the impression that testicles would rupture if not drained regularly.
She attributed this to something she had overhead someone say in jr high, and had apparently never figured out otherwise.
It kinda makes sense. Why would the sack be so big and stretchy if it didn't need to hold balls that would expand. And why would guys have different sized ones if some of them weren't draining them more often than others.
The ensuing conversation was a difficult one. Partially because it stopped the previous activity, partially because she had a lot of questions, and partially because it wasn't clear if the frequency with which she wanted to prevent my testicles from exploding would decrease.
Luckily, the conversation went very well, and they did eventually explode in the usual way, which was much more entertaining for her than before, she said. It also led to a lot of fun as she developed an almost fetish about feeling the event happen whenever activity would make that possible.