My first race ever, I'm friggn stoked. I put all my gear on and noodle over to my then mentor's car so I can show off how awesome I am. Nevermind that its 40* out and raining and I don't even have a pair of tights or a long sleeve jersey; I'm wearing calf-high wool socks and a long sleeve shirt underneath my jersey, and my legs are covered in hair longer than the hair on my head. When I pull up to his car, I go to stop but don't unclip in time, and wind up falling over at his feet while the whole field i'd be riding with watches me flop around like a fish out of water.
Runner up: Stage 3 of the GMSR, I'm placed 5th on the GC. The peleton is about 3 minutes down on a 1 man break, and we aren't gaining any ground. I'm pulling the peloton into a nasty headwind/crosswind and am getting fed up that nobody else is working with me. I go to pull off multiple times, but the #2 guy sticks on my wheel. I flick my elbow, nobody comes around. I'm pissed. I yell "Anyone else going to pull? Anyone? Bueller? Bueller?" Nobody responds, so I throw down the hammer and gap them a bit, then let them catch me and fall back into the peloton. As I'm settling back in, the yellow jersey taps me on the shoulder and goes "hey man, you're supposed to peel off into the wind." This explains why nobody would come around me, as each time I tried to peel off I was peeling off away from the wind.
edited for lucidity