Your girlfriend would never let you watch her do yoga and would always do it when you weren't at her place. Eventually one day you decided you had had enough. After "leaving", you shrunk yourself outside her door and snuck back in while she started. You couldn't resist getting as close as possible.
This turned out to be a bad choice as her soft bare foot came crashing down on you while she was changing from one position of hers to another. Even if you had had time to scream, she wouldn't have heard you. Your body was smeared against her mat and never even noticed.
Nobody would ever know what happened to you.