Yes, I do it all the time. It's better than having a raw nose from constantly wiping it.
Start by practicing into a tissue instead of blowing your nose the normal way. Once you're comfortable with that, move on to actual outdoor snot rockets.
Couldn't help thinking this song was appropriate for this thread...
http://www.youtube.com/watch?v=jDZ8SCES0YE
2011 Surly LHT
1995 Trek 830