Give ’em Hell (often excl.)

What does the idiom “Give ’em Hell (often excl.)” mean?

Definition:

Express something passionately to a group

For example:

“Don’t be afraid during your speech—people want to hear strong opinions on this. Give ’em hell! “

Notes:

This is very colloquial. A common use was in the campaign of US president Harry Truman, where the slogan “Give ’em hell, Harry!” was used.