The closest to that for me was being a just out of high school employee at an interesting post production facility that had some talented people in the engineering staff. I was a kid in a candy store, but all electronics and video/film based stuff. The engineers were probably taken off guard by my incessant questions of why/how/huh until they eventually realized that I wan't being a pest but actually learning what they were sharing. At some point, the questions were advanced enough they wanted me to switch departments. Definitely the best OJT situation I've ever been in, but that was 30 years ago now. damn.