There are different meanings. We need context. Here are some possible ones Take a bullet / get shot Take a shot of whiskey Take a punch

It's an American expression that means to punch someone. E.g. He took a slug at me. Take a slug at him. He slugged me. :)

It really all depends on the context... The above answers are correct. There are other meanings of "slug". https://www.merriam-webster.com/dictionary/slug