I had my first bleeder last night. Popped the set out and "BWWWUUUUUUSHHHHHH" - a giant stream of blood ran out of the hole:
It freaked me right the hell out, but I had the presence of mind to cup my hand under it (cupped! like I was getting water out of a lake or something!) and salvage my pants - only the top of my underwear got all gross before I slapped a paper towel on the river of blood.
Note to self: Never, ever do a set change without something absorbent at the ready.