The Only Way Is Essex pair told the magazine about what they get up to over the holiday period.
"Oh my God, I hate opening presents," Sims said.
"I have a proper phobia about it. I can't open any gift in front of anyone."
She added: "My face feels red, I can feel my heart pumping and I get so anxious I can barely speak.
"I have to ask people to leave the present in a corner and I'll open it later."
Sims said of Christmas dinner: "I eat until I'm sick! I have dinner at my dad's then dessert - cake and pudding with double cream - then I'll go back to my house and have turkey and stuffing sandwiches with crisps and chocs in front of the TV."
Sims revealed: "I'll be wearing a reindeer jumper - the reindeer even has big eyelashes on, Essex-style!"
Read the full feature in Nuts magazine, out now.