To expel mucus from just one nostril by blocking the other one. Ew, that's so gross—quit blowing snot rockets!
blow a snot rocket
verb
See blow snot rockets
blow snot rockets
and blow a snot rocket
tv. to blow gobs of nasal mucus from one nostril at a time by blocking off the other nostril with a thumb. Bob is always blowing snot rockets! How crude! He tried to blow a snot rocket at the dog, but it kept right on barking.