This is ENGLISH.
Whoever the hell said that it's gonna be used properly? With the common stupidities, shortcuts, misuses, etc. of various words, something like that could happen.
I mean, if you played a Video Game, and killed a

load of enemies with your machine gun, it'd be called "quite a reap".
Reap is sometimes used to mean stirring up.
Besides, if you replaced "reap" with "meet", it would make a LOT more sense to change it to:
"You call
ed down the thunder, now meet the whirlwind."
I believe the "You call down the thunder, 'n' I'll reap the whirlwind" is some kind of refrence to nukes. Don't ask why, I just think it is.
Besides, whenever I hear him say that, uit sounds exactly like what I said, to me atleast.
DT agreed that it sounds like "reap".
"So U_B's crazy... Bleh "
True,(not only is it true, but I'm proud of it, obviously), but insanity is not a basis for incorrectness, except in the case of dellusional/illusional/some-other-distortion-in-physical-and/or-mental-perception...