Why is my dog always rubbing his butt on the floor?

Because it itches.

Probably needs to be treated for worms

His a.ss itches, duh...

he's itchy

cause there butt iches my dos do that to

means he's turned on, what have you been doing in front of him?

Okay, I will try to answer seriously!! The most common reason, is the anal glands are becoming impacted. A Vet can express them quickly and easily.
The other could very well be a worm problem, so have his feces checked for that.

may have worms.

He doesn't have any toliet paper so he uses ur floor for wipe.

he might have worms check with a vet to be sure

you don't rub your butt on the floor?

he probly has worms please check out patronapits.piczo.com

Trying to rub out the pattern on the linoleum?

its called itching

He has worms. Eating human food with flour in it will cause it among other things that dogs can get into.

He is rubbing his butt on the floor he probley have worms or it might just itch....

He could have worms.

Get your dog to the Vet. Your dog has worms.

Because they know its annoying and his butt probly itches