I once caught a catfish in the Monongahela river outside of Pittsburgh that scared me it was so large. Thought I'd snagged a log. When it got close enough to shore to shine the light on the thing, its head was a good two feet across and the tentacles seemed to go on forever, as did the part behind the head.
I knew right what to do.
Pulled out mah knife, flicked it open with my thumb -- and cut the line!
--Mac