Why should you remove stingers carefully and quickly?

ANSWER:

Because the stinger of the honeybee has barbs on it, it will stick and stay in your skin and it has a muscular contraction that continues to pump venom into your body. Remove it with a sharp knife or piece of paper. Don't use your fingers because this will squeeze the venom sac, injecting more venom. The honeybee stinger is the only one with barbs.

You can scrape it out with a fingernail if a knife or paper isn't to hand.