| flipped(silly, foolish, mad, insane, unwise) |
| flipped out(expression, silly, foolish, crazy, mad) |
| fond |
| freaked out(expression, silly, foolish, crazy, mad) |
| fruity(silly, foolish, mad, insane, unwise) |
| funny(light, unusual, wild, strange, crazy) |
| futile(adjective, ridiculous, absurd, pointless, vain) |
| harebrained(extraordinary, silly, foolish, amazing, dubious) |
| humorsome(careless, unstable, unreasonable, unpredictable, changeable) |
| idiosyncratic(extraordinary, unusual, wild, strange, crazy) |
| impulsive(adjective, informal, unusual, careless, lively) |
| inane(adjective, wild, silly, foolish, stupid) |
| irrational(adjective, informal, unusual, wild, strange) |
| irregular(unusual, strange, crazy, unpredictable, changeable) |
| ludicrous(adjective, light, wild, silly, foolish) |
| lunatic(adjective, informal, silly, foolish, crazy) |
| mad as a March hare(expression, idiom, silly, foolish, mad) |
| mad as a hatter(expression, idiom, silly, foolish, mad) |
| maudlin |
| mentally strange(expression, silly, foolish, mad, insane) |