Scott Disick and Tyga -- Bros and Woes (PHOTO)

Scott Disick and Tyga had a lot in common Monday ... they were both under fire by hot chicks with big butts.

Scott and Tyga were filming Khloe Kardashian's TV show when they took a break and commiserated.

As we reported, Tyga's baby mama, Blac Chyna, has been hanging with Rob Kardashian which we're told has royally pissed off Kylie and company.

As for Scott, Blac Chyna's BFF, Amber Rose, was hanging with Scott in Vegas over the weekend and started following him on Instagram ... not particularly pleasing to Kourtney Kardashian.