OBVIOUSLY

Black as midnight
Bump, bump, bump
Against the table
Door and stump

He bumps my leg
My foot, my hand
He bumps his food dish
Dry or canned

He bumps the dog
Bumps the fish
He'd bump a camel
A sandy wish

You might just think
He must be
A goat named Billy
Guess we'll see

You would be wrong
Hmmm... stumper
'Cause he is my cat

...and for obvious reasons that I don't think I need to go into, I named...

Him BUMPER