Farmer's Blow Technique:
For the left nostril, leave the left hand on the bars; raise the left elbow; tuck the head into the hole created by raising the left elbow; take the point of the gloved index finger of the right hand and push it against the opening of the right nostril like a cork in a bottle (don't compress the nostril from the side); point the chin to the left and aim the left nostril at a point on the ground two feet to the left of the rear axle; take a deep breath through the mouth; and, explosively expell air and snot from the left nostril.
Do not do this with a crosswind from the left, as it will blow the snot back against the rider and bike.
For the right nostril, substitute the word right for every occurence of the word left in the instructions above, and use the index finger of the left hand for the cork in the left nostril.