Common Errors in English: Bad or Badly
Bad is an adjective; badly is an adverb. Don’t get them confused.
I did bad on my English exam.
I did badly on my English exam.
By the time the speech ended, he wanted to go home bad.
This sentence is possible, if he wants to become a criminal before going home. (Perhaps he’s going to murder the speaker?)
By the time the speech ended, he badly wanted to go home.
But… remember the rule about sense verbs. If you want to talk about how something looks or smells, or how someone feels, use bad.
She felt bad about forgetting her brother’s birthday.