You did something wrong and you regret it.
mark:i put the buckets in the shed
shawn:ok now go put the hose up-.....what did you do bad
mark:i just did a bad, i regret the thing i did (song)
it means you do something and you regret it
mark:i put the buckets in the shed
shawn:okay now put the hose in the-what did you do this time??
mark:a bad thing