It’s Tony’s nickname for Thor
According to an Screen Rant article:
When Thor enters the Quinjet he has a hard time gaining access to its
controls. The ship asks for voice recognition input and he uses many
different names including, “Thor,” “Thor, Son of Odin,” “God of
Thunder,” and “Strongest Avenger.” However, the name that ultimately
gains him access is “Point Break.”
Point Break is the name Tony Stark gave Thor in the first Avengers
film because of his resemblance to Patrick Swayze in the 1991 film,
Point Break. In this surfer-robber ’90s movie, Swayze sports long
luscious blonde hair, much like the God of Thunder’s flowing locks,
and Stark is more than happy to point this out from time to time.
Thor doesn’t like this nickname (it’s got an edge of mockery), so naturally he’d be upset. Plus, Tony came up with it while criticizing Thor:
TONY (to Thor): It’s a stabilizing agent.
(to Coulson): I’ll fly you there. Keep the love alive. Means the portal won’t collapse on itself, like it did at SHIELD.
(to Thor): No hard feelings, Point Break. You’ve got a mean swing.