Lazy

OK, I’ve done a little Googling on this but can’t find anything particularly helpful. So I turn to you, dear reader, and your worldly knowledge… well your worldly opinion anyway…

The saying “Thanks a bunch” has cropped up three times in the last 10 minutes. Each time I’ve read it I’ve put my own understanding of what the phrase means and each time I’ve been wrong. Without wanting to sway you either way I need a straw poll:

What is the underlying tone used when saying “Thanks a bunch!”? Answers in the comment box please.