Imagination

"I disgust myself!
It's all just my imagination!
All my imagination!
But wow, my imagination's really developed

Holes

"Humans are born from holes, and to holes they return"

from: Aquarion Evol episode 9

To be scared...

"Does he even know what it means to be scared?"

"I don't think he deals with such 'nonsense' "

from: Boy of the Female Wolf
hahaha, I laughed until my stomach hurt :D

What is it?

"That cannot be a girl! No way! It probably isn't even human either...

from: Boy of the Female Wolf

You should really read this series, there are too many funny sentences :D

Ghosts

"Sometimes I hear ghostly footsteps in my office''
"Would you be less bothered if they walked more quietly?"
Rasetsu no Hana, chapter 7

Idiots

''Only an idiot can understand how to treat an idiot''
Dengeki Daisy

I like this one, because it's simply funny :D
But it is true, if you were to think about it...

Dogs & Cats

''I like dogs, I also like cats, but cats don't seem to like me...''
From the autor of Tenshi Ja Nai!

I thought it was very funny how he/she said it, but maybe it isn't so fun for you...