a large amount of snot running down on your mustache causing an icicle.
SNOTSTACHE: When a person with a mustache exercises in extremely cold weather they grow a snotstache.
what forms when a child has so much mucus running out of it's nose that it begins to flow out of both nostrils and over the lip and/or down to the corners of the mouth. In extreme cases, this can extend beyond the corners and run down to the chin, creating a sort of "Fu-man choo" style of snotstache.
"Eww...I dropped my kid off at daycare today and that sickly kid with the snotstache was there. I guess everybody's catching something this week!"