The England full-back completed his move from Tottenham to the Spanish club in the summer, where Costa is also currently plying his trade.
Costa has a reputation for being hot-headed with a fiery temper, but Trippier explained his other persona as the joker of the dressing room is more accurate.
“He calls me Rooney ten times a day!" Trippier told Marca. "He's like that all the time and it makes me laugh. But it's Diego. I don't mind. We all find it fun.
“I like him to make jokes every day. I knew him from the Premier League and he's the funniest player I've ever played with.
“There's a great atmosphere on the team, joking with each other, but Costa is the funniest. He also says I look like a boxer – but I don't think so!
“It's been easy to adapt here. The weather is nice. The food is incredible, better than in England. People welcome me and make my family smile. It makes it easier for me."