Snap! There it is, that moment every angler knows, and maybe the most frustrating part of the whole sport.
After spending some time, perhaps quite a bit of time if the flies are small and the air is cold, tying on your weapon of choice, your tippet snaps. It's a moment of grievance followed by profanity followed by frantically checking to see if you've fumbled the knot or if the tippet's gone bad.