If you have a lot of liquid snot in your nose, and your near a sink, here's an effective (yet really disturbing ) way to get rid of some of it.
Youve all caughed up flem before I assum (green stuff from the throat). All you need to do, is snort all the snot you can from you nose, into your throat, this is where most people swallow, BUT NO NO! don't swallow it! caugh it up like you would flem and spit it into an appropriat place at your own leisure. This is not the type of thing you try to do in public, but if your in a private area, or alone outside, this helps keep things clear for a while till you can get to a kleen x box or what not.
I'd suggest being ready to spit, because holding that stuff in your mouth is just not a cool feeling. :-D