cockamamie, cockamamy, goofy, sappy, silly, wacky, whacky, zany (adj)

ludicrous, foolish

"gave me a cockamamie reason for not going"; "wore a goofy hat"; "a silly idea"; "some wacky plan for selling more books"

balmy, barmy, bats, batty, bonkers, buggy, cracked, crackers, daft, dotty, fruity, haywire, kooky, kookie, loco, loony, loopy, nuts, nutty, round the bend, around the bend, wacky, whacky (adj)

informal or slang terms for mentally irregular

"it used to drive my husband balmy"

wacky (Adjective)

Of a person or their behaviour, zany.

wacky

Eccentricity (also called quirkiness) is an unusual or odd behavior on the part of an individual. This behavior would typically be perceived as unusual or unnecessary, without being demonstrably maladaptive. Eccentricity is contrasted with normal behavior, the nearly universal means by which individuals in society solve given problems and pursue certain priorities in everyday life. People who consistently display benignly eccentric behavior are labeled as "eccentrics".