The Elephant Matriarch from Dumbo boos when pop culture things receive Negative reviews and are a Critical Failure and even booing at Villains and bad people. She even Boos when people have finished Booing.
The sounds of her boos are from the Ancient Booer from Princess Bride:
The Princess Bride! Queen of Garbage!
From 1:35 to 1:41, She boos and from 2:11 to 2:20 She starts booing and slurring by saying Rubbish, filth Slime Muck and boos again
(After her first Boo) BOO!!!!
(After her second Boo) BOO!!!!!
(After her Third boo) BOO!!
(After her Fourth boo) BOO!!
RUBBISH!!
FILTH!!!!
SLIME!!!!
MUCK!!!!
BOO!!!!
(After booing twice at the villain or a pop culture thing) BOO!!!!!!! (As the camera zooms quickly into her mouth and fades to black)