rub up
To cause something to be raised up as a result of rubbing it. A noun or pronoun can be used between "rub" and "up." Don't rub up my hair like that! Cats hate it when you rub their fur up by petting them from back to front.
rub something up
to raise something, such as the nap of a rug, by rubbing. When you run the vacuum cleaner across the floor, you rub the nap of the rug up and get the dirt out. Don't rub up the nap.