disbelievable 

Not credible; warrants non-belief

The idea that Oswald acted alone is disbelievable in the face of Kennedy's actions which upset the Mob and the Cubans.

If you look at the Henne family's background, its disbelievable that the family wasn't perpetrating some sort of hoax.

Shakesphere had only an elementary-school education. It's disbelievable that he wrote Hamlet.

disbelievable by blogmandu October 20, 2009

disbeliefable 

When in disbelief of something believable.

The fact a natty ice beer can taste good ,is disbeliefable.

disbeliefable by demsome October 31, 2017

disrebelievable 

disrespectful and unbelievable

Oh my gosh, that was so disrebelievable!

disrebelievable by mads808 February 9, 2017

Dumbelievable 

When something so dumb happens that you aren't sure if you believe it or not.

"Jason tried to eat the shell of the lobster."

"I thought it'd be like chips."

"That's dumbelievable, Jason."

Dumbelievable by JimmyTheSmack June 2, 2018