1. adjective, slang Clumsy or incompetent, especially due to being careless, foolish, or out of control. Potentially offensive due to originally having been a derogatory term for someone with spastic paralysis or cerebral palsy. My parents are making me take my spastic little sister with me to the mall. He gets so spastic when he's around that girl he likes.

2. noun, slang A person who is clumsy or incompetent in such a way. Potentially offensive. I can't believe I sent that embarrassing email to the entire office. God, I'm such a spastic! You're always messing up our games with your stupid antics, Tommy! Why do you have to be such a spastic all the time?