I've had two nasty 'knob probs'.
When i was 15 i had a really aggressive wank [like you do at that age], and just when i was about to come i felt an intense pain in the left side of my dick. It immediately swelled up and ever since then its leant to the left. I went to the docs, and he said if it gives me problems pissing and cumming i would have to have an operation to straighten the inside. No thank you!
Second time i shagged a girl of 'questionable morals' without wearing a condom, even though i had a bleeding cut on the bit of skin that bisects your bellend. [when you're a teeneager you think you're invincible]. In the morning my cock was massive, but it was all FORESKIN. When i say massive i really mean it - it was like a tin of something. I was terrified and i cycled to casualty and demanded a doc look at it. He said a bit of shit must have got in the cut, hence the enormous swelling. How it got there i don't know, because i didn't have anal sex with her