Air carrier Flight Attendant reported avoiding an inadvertent escape slide deployment when catering tried to open an armed aircraft door without an ok to open" hand signal. Escape slide did not deploy."

Narrative

Flight ZZZ1-ZZZI wanted to report unsafe incident with catering after we arrived in ZZZ. We heard a knock on aft door from catering. Next thing the catering opened the aft ac (aircraft) door while we were still in jumpseat. We screaming for him to stop opening the door; fear that he would hit the slide housing with the jumpseat still in open position and cause slide deployment. All 4 fa yelled at him to stop opening the door. He did stop then proceeded to close the aft door and that's when we were able to get up from the jumpseat. He then proceeded to open the aft door again. However the caterer said to us that he didn't need the fa to give him thumbs up before he opened the door. We explained to him that we have no where to go with 4 fa in the back galley and passenger not yet deplane. He then said to us that we are not working together he needs to cater 5 flights in 20 mins. I said to him what he did is not safe. He can blow a slide; the way he is forcing the door open while we were still in jumpseat. He walked away. Then he came back once again forcibly his way into the galley again with all 4 fa in back galley. He started pulling the carriers and trash carts while I am inches from him creating a very unsafe environment. He almost caused a slide deployment trying to open aft door with jumpseat still in open position. It was not safe to rush to do open the aft door without checking to see if crew was still occupying the jumpseat. He went ahead rushed catering even though the back galley was full with 4 crew still waiting for pax (Passengers) to deplane. There was no room to change carrier and pull trash cart with 4 FA still in back galley.