Just the other week she flat out told Franky to NEVER BE CHOPPER AGAIN and how she hates Franky as Chopper and to not talk, ever. Any time something bad happens, Robin will say with a straight face, and sometimes a smile, some morbid, depressing fact that is nothing short of the truth. She does the straight man shtick far better than Zoro. Zoro's best comedy moments come from his complete lack of compass or sense of direction.
I just think you have a selective memory, Bebpo!