Two kooky elderly siblings who share a Brooklyn home despite dueling restraining orders had a knockdown, drag-out fight that landed both in jail — over a roll of toilet paper.

Howard Meltzer, 67, and Bernice Meltzer, 72, who constantly squabble and call cops on each other, took their rivalry to comical proportions Tuesday night when the sister allegedly dashed to her bedroom with the last roll of Charmin and locked herself in.

Howard — who walks with a cane and sometimes uses a motorized scooter — banged furiously on her door and didn’t stop until almost midnight, a law-enforcement source said.

“Five hours he was knocking on that door,” a law-enforcement source said. “It sounds like he absolutely had to go bad.”

Howard said he had gone into the bathroom and found barely a square of toilet paper.

“The roll was full when I went there in the morning,” he told The Post as he left Brooklyn Criminal Court yesterday after being released without bail. “She unloaded a whole roll and left just a little, and when I looked up to the reserve, it wasn’t there.”

Howard soon found Bernice had taken the last roll into her room. He banged on the door.

“I said I want the toilet paper back by 1 [a.m.] or I’m calling the police,” Howard recalled.

At one point, he called a grocery store asking it to deliver two packs of Charmin to the Midwood home.

“I ordered it and would have paid anything. I needed it,” he said.

Howard said his sister put the TP back at around midnight.

But by that time, she was fed up with her brother’s raging and called 911, summoning officers to the home, which they jointly own.

The siblings were under mutual orders of protection, and cops charged them with violating them.

“It’s crazy that you have two people fighting over toilet paper. I can only imagine what was going on with these two,” a law-enforcement source said, adding, “When you gotta go, you gotta go!”

Bernice appeared before a Criminal Court judge Wednesday.

“The judge had a copy of the complaint in his hand and started laughing,” a law-enforcement source recalled.

After her arraignment, Bernice was hit with a misdemeanor criminal-contempt charge and released without bail.

Howard was arraigned on felony criminal-contempt charges last night and released on his own recognizance. He said he is allowed to return home — but might stay with a friend.

Additional reporting by Jamie Schram