Thor and Loki haven't been on the best of terms in recent years, which is understandable given that the latter has tried to conquer both Earth and Asgard, and actually succeeded in later seizing the Asgardian throne after faking his death. It's at the point now where Thor has given up trying to redeem his adoptive brother, but as the below Thor: Ragnarok clip shows, just because they're still on the outs doesn't mean they can't have a little fun during their latest team-up.
One of the newest clips for Thor: Ragnarok (shared by Fandango), which appears to take place after the God of Thunder's tussle with Hulk on Sakaar, has Thor and Loki riding up an elevator to catch some of Grandmaster's minions by surprise, with Thor telling his brother that their paths diverged a long time ago and Loki saying it's probably for the best they don't see each other again after this adventure is over.
But after the hard truths have been dropped, Thor suggests they pull the classic "Get Help" ruse. Loki's clearly not game for it, but when the elevator opens up, he's decided to play along and fake being injured. The end result is Thor tossing Loki straight into their armed soldiers in a moment reminiscent of when Wolverine and Colossus pull off the Fastball Special in the X-Men comics. Thor gets a kick out of it, but Loki still finds being thrown like a rag doll humiliating.
In the Marvel Cinematic Universe, Thor and Loki have both been around for over a millennia, and for most of their time together, they were the best of friends. But ever since the events of the first Thor movie, the two have taken drastically different courses in life, with Thor growing more humble and using his mighty abilities as a superhero, and Loki now more concerned with becoming more powerful, which he accomplished to a degree at the end of Thor: The Dark World when he tucked Odin away and disguised himself as the All-Father. It's only recently that Thor even learned about this deception, so it's not surprising whatsoever that he's is finally through with trying to find the good in Loki.
The brothers are civil enough that they can still work together, be it with the "Get Help" ruse or later teaming up with Valkyrie and The Hulk to stop Hela from destroying Asgard by means of the apocalyptic Ragnarok event. It remains to be seen where their relationship will ultimately end up at the conclusion of Thor: Ragnarok and going into Avengers: Infinity War, though given that the Infinity War footage from D23 showed Loki handing the Tesseract to someone (presumably Thanos), one wouldn't be blamed for thinking that things will only get worse from here.