So there was a lot hate on the music selection for this movie. But I personally have to say, it makes total sense and I loved it. Being born in 1989, I watched a lot of Full House growing up, and I therefore remember the apex of coolness at the time was Uncle Jesse playing with The Beach Boys at the Super Bowl (maybe it was just some random football game, I don't know). But the point is, barbershop rock music was the shit in the 90s because of Uncle Jesse.
(That said, I also did not watch the movie once I found out this was "Surf Ninjas" and not "three ninjas", which I watched way too much as a child considering it's about three white boys who are ninjas, and whose grandfather is played by the actor who was Mr. Myagi in Karate Kid.)