1. someone who actually partakes in smoking crack.
2. someone who conducts themselves in a strange manner, in the manner of a crazy person, a hobo, or a diluted senial old man.
3. someone who does or says something that doesn't make sense or is contrary to something previously done/said.
1. Your mom needs to lay off the pipe, she's such a crackhead.
2. My friend was running through the street yesterday wearing pink spandex and screaming "poseidon is coming with his trident of fury," she must have seemed like such a crackhead.
2. Your dad told me he loved fishing but would never go fishing before sunrise or if it was light out, he's such a crackhead.