It was 6th grade. My standards were low and I was hanging out with a chubby Asian girl. I was absolutely clueless that she liked me, and when she went in for the kiss I panicked and froze up. That was bad enough, but I also had a big scab on my lip from falling on the ground a couple days ago while skating.
Unfortunately for her, she went for a french kiss right on the scab. She bit the scab right off, and immediately recoiled in disgust, spitting the scab on the floor.
Thankfully I haven't had a kiss that bad since.