I saw a post using "bad people" as negative numbers as an analogy for -(-16)=+16:
"If bad things happen to bad people it's a good thing."
I don't like bad things to happen to anyone. An analogy I use is "taking away a negative".
If you are sick and go to the doctors, and she takes that illness away, it's a positive thing. So:
take away illness is subtraction of a negative -(illness)=positive or -(-9)= +9
Any other suggestions?