This means their arms are occupied and you can go for the choke.
The Rear Naked Choke From Hell
Make sure the triangle is locked on the top side of your opponent and keep the pressure on.
For everyone favoring the rear naked choke, this is, not good news.
However, there are instances where is still the best method of hip control. In real circumstances, people look to block the arms, open be hard to complete palms and everything else to defend the choke.