I'm female 25 years old. My most embarrassing situation happened a few years ago when I was in college. My roomie had gone away for the weekend and I was alone. One evening, after drinking a little wine at a party I came back to my room and decided to masturbate. I locked my door, stripped naked, put on my earphones (blasting) and went to it with a vibrator!
What I didn't know was that my roomie thought I was also going to be gone for the weekend, and gave her key to a friend in case the friend "got lucky". I was in the middle of my "work-out", my headset blasting, my eyes squeezed shut, when the door opened and a girl and a guy walked in!
They stood, frozen in shock while I lay writhing on the bed. I didn't hear or see them! After what could only have been a few seconds, something made me open my eyes! I almost had a heart attack! They mumbled an apology and ran out! I seriously considered a transfer.