Neville was extremely bothered by Barty Crouch Jr disguised as Mad-Eye Moody using the Cruciatus Curse on a spider during class. This was mainly because Neville's parents were tortured by Death Eaters using this very curse, and seeing it being used in front of him must have caused trauma. Interestingly, Barty Crouch Jr, who was disguised as Mad-Eye Moody during this class, was one of the four Death Eaters who used this curse on Neville's parents.