I went on a date once and I really wanted to impress the girl, so I went to a flower store and bought some exotic looking flowers and hid them under the table at the restaurant. Then when she sat down I told her I had a surprise for her, and I convinced her to close her eyes. I grabbed the flowers and put them right under her nose thinking she would smell them and smile. But instead she just started violently sneezing. Her face started to get red and splotchy and I asked if she was ok. I could tell she wanted to say something but she couldn't stop sneezing. I imagine it was along the lines of 'I'm allergic to these flowers asshole' but I'll never know. She ran out of the restaurant embarrassed and I never heard from her again.
One night in college a friend of mine brought an entire bag full of alcohol for a small party in our dorm room. I met him down in the lobby to sign him in, and walked into the elevator to ride up to the 6th floor. It was entirely obvious what was in the bag, but it was a little too late to hide it and I wasn't very worried since the only person who would care was the building RA, who I had never seen once since orientation. On the 5th floor the elevator opened up, and that was exactly who walked in. We were written up and assigned the most depressing task imaginable for a college student - emptying every individual beer can into the bathroom sink under supervision.
Right before an important management meeting at work, I realized I really had to piss. On my way to the meeting I ran into a bathroom and up to the urinal. Right before I unbuckled my belt, the door opened and my boss walked up to urinal next to me. He started the uncomfortable urinal small talk which for some reason made it psychologically impossible for me to pee. The break in conversation made it completely obvious that I was standing there in silence, and I had no choice but to pretend like I had finished ahead of him. To make matters worse, he walked with me directly to the meeting, preventing me from going to another bathroom, and I had to sit through the meeting with my legs crossed the entire time.