Using Bad Badly or Using Badly Bad

Over the weekend I watched the movie Kiss, Kiss, Bang, Bang (2005), staring Robert Downey Jr. and Val Kilmer. In this movie the two main characters go back and forth correcting each others’ use of bad and badly in a humorous way. After Robert Downey Jr. tells Val Kilmer that he should say "sleep bad" not "sleep badly," Kilmer responses indignantly, saying “Who taught you grammar? Badly’s an adverb. Get out. Vanish.” This comedic exchange led me to this week’s Tips and Tricks topic: Using Bad Badly or Using Badly Bad.

Here’re the facts: it is correct to say you feel bad when expressing an emotion. Bad is an adjective that modifies the noun.

Saying “I feel badly” implies that there is something wrong with your sense of touch or something wrong with the way you feel. It’s like saying you don’t feel things correctly.

Badly is an adverb - it modifies a verb. When someone says “I feel badly,” the adverb badly modifies the verb (feel).

Think of it like this: would you say, “I feel madly” or “I feel sadly”? No, you’d say, “I feel mad” or “I feel sad.” It works the same with bad and badly.

This tip applies with all verbs that describe our senses (feel, taste, smell, etc.). For example:

• “I smell bad” means “I have an offensive odor.” / “I stink.”
• “I smell badly” means “My sense of smell doesn’t work correctly.”
• “That tastes bad” means “That doesn’t taste good.”
• “That tastes badly” means “That things sense of taste works incorrectly.”

Additionally, after most other verbs (excluding those that describe our senses), it is correct to use an adverb (such as badly). For example:

• “My review went badly.”
• “As a child, I behaved badly.”

Therefore, in Kiss, Kiss, Bang, Bang, Kilmer’s character is correct in saying “I sleep badly” because badly is an adverb and the verb (to sleep) does not describe the senses. Don’t worry, Robert Downey Jr. — it’s a common mistake.