goofball

Etymology

goof + ball

noun

1. (informal, often derogatory, sometimes endearing) A foolish or silly person or animal.
   If that goofball would put half the effort into her studies as she does into her juggling, she might do very well.
2. (informal, pharmacology) A pill or tablet containing a pharmaceutical which has hypnotic or intoxicating effects, especially a barbiturate.
   Strong Cobb & Co. of Cleveland announced a new barbiturate which in overlarge doses will turn the stomachs of "goofball" addicts and would-be suicides. April 27 1953, “Capsules”, in Time

adj

1. (informal) Silly.
   He announced, with his usual goofball humor, that he'd like to marry me!