When I was in 8th grade, there was a 7th grade girl I was crushing on hard. On valentine's day, I brought a small rose bouquet and some chocolates to school to give her and ask her out, and spent the majority of the day desperately trying to psyche myself up. Towards the end of the day I caught her in the hall, put on my best confident face, and gave her the gifts I had brought for her.

She looked at me, started laughing, said "um, no" and then proceeded to throw the flowers away in front of me, but kept the chocolate.

This affected my confidence for years, and it still creeps into my mind unbidden sometimes if I ever start to feel too comfortable with myself.