Being caught masturbating, usually refered to a teenage male. It is extreamly embarrassing for both parties, especially if you dont know they are there and do something that reveals your erection in full view. You dont really want your mum or sister seeing what your manhood looks like at its best.
One time i was masturbating in my room fully naked when my brother came in and I was caught in the act. He could not have walked in at a worse time as I was about to come. I quickly stood up to hide myself but i was past the point of return and sperm pumped into my palms as i hid my dick. It dripped through my fingers and the orgasm was so powerful i let out a few pathetic gasps. I still cannot look my brother in the eyes.