Weird
General:
* Bizarre
* Eccentric
* Outlandish
* Peculiar
* Strange
* Unconventional
* Unorthodox
* Wacky
* Out there
* Quirky
More intense:
* Grotesque
* Monstrous
* Surrealistic
* Uncanny
* Eerie
* Ghoulish
* Absurd
* Preposterous
Crazy
General:
* Bonkers
* Deranged
* Frantic
* Giddy
* Nutty
* Raving
* Wild
* Zany
* Outrageous
* Unhinged
More intense:
* Demented
* Lunatic
* Maniacal
* Psychotic
* Delusional
* Hallucinatory
* Rambling
* Hysterical
* Frenetic
Insane
General:
* Irrational
* Mad
* Mentally unstable
* Unbalanced
* Unsound
* Deranged
* Delirious
* Demented
* Psychotic
More intense:
* Incurably insane
* Lunatic
* Maniac
* Pathological
* Fanatical
* Obsessive
Other related words:
* Baffling: Difficult to understand.
* Bewildering: Confusing or perplexing.
* Bewitched: Enchanted or charmed.
* Bizarre: Very strange or unusual.
* Daft: Stupid or silly.
* Idiotic: Extremely foolish or stupid.
* Incoherent: Not logical or clear.
* Ludicrous: Absurdly ridiculous.
* Outlandish: Extravagant or bizarre.
* Preposterous: Ridiculously unreasonable.
* Ridiculous: Laughably foolish or absurd.
* Unfathomable: Impossible to understand.
* Whimsical: Fanciful or capricious.
Note: The intensity of these words can vary depending on context and how they are used.