Dwayne Johnson found a "really painful" lump in the shower, then faced 24 hours of not knowing whether it was cancer. The Rock's scare turned out to be epididymitis, not cancer, but his instinct to get checked fast is the one every guy should copy. Here's what his story teaches us about self-exams, why pain doesn't rule cancer out, and how TCF helps when the answer isn't "I'm fine."