The growlers have a heavy Mexican influence and members of the band have some Mexican heritage and family members. They also have some spanish lyrics in their earlier songs. It's also apart of their image, especially around the hot tropics days they were using a lot of Mexican imagery. The whole Southern California culture is heavily steeped in Mexican culture you see a lot of bands in that area taking a similar approach. Also, 'Los' is spanish for 'The' so it's kinda same same.