I was doing an apollo-style moon landing with the separate CSM/LM. My LM had come up, and successfully rendezvoused with the CSM. Everyone transferred over fine, and since my LM was just a lander-can, 4 solar panels, and a bunch of RCS, I undocked from it. I then time warped halfway around my munar orbit to eject into a kerbin intercept orbit with the least fuel, and by that point the tiny forces from docking had driven the LM far out of sight. So I started up my SM engine for TKI, and about 20 seconds later, BAM out of the blue my totally-forgotten-about LM comes crashing into my rocket. Luckily it directly impacted the SM not the command pod, so Ed, Ademy, and Shepdorf were alive, but left in a wildly spinning command capsule with just a docking port and a decoupler attached, surrounded by a cloud of debris. Bill, Bob, and Jebediah went up and saved them though. Probably my finest hour in KSP too