Used when someone unintentionally sees or hears something private or personal. I did not mean to, but I walked in on her personal diary.
Pro Tip 2/3
Embarrassing Moments
Emphasizes awkward or uncomfortable situations, usually when privacy is expected. He was so embarrassed when his sister walked in on him singing in the shower.
Pro Tip 3/3
Unintentional Interruption
Stresses the accidental aspect of interrupting an ongoing activity or situation. She seemed annoyed when I accidentally walked in on her phone call.