Answer:
Kills the bad ones and the sad ones. Tightens to fit, so one size fits.
It's like food but water kills it. What is it?
What word is a plural, but when you add an "S" to the end, it becomes singular?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.
My life can be measured in hours, I serve by being devoured. Thin, I am quick. Fat, I am slow. Wind is my foe.
Why is the letter B always cool?