Used to describe an unfortunate event which could have been far worse
in its outcome and therefore actually lucky.
That tornado tore off part of your roof but did not destroy your house and nobody was injured. Apollo 13 luck!
Completely overwhelmed with work or other responsibilities. Metaphorically, I'm about to drown in whatever I happen to be immersed in. water, shit, etc.
I'm sorry I can't meet with you. I'm up to my ears in work right now.