Boos really piss me off more than hammer bros; when you turn around, they usually vanish or cover their faces. Sometimes, I just can't get a clear shot at jumping on them without turning around---I usually miss or take damage (especially lose a life).
goombas. have you ever thought of how many times that you have jumped, aiming for a goomba, landed just shy and had the stupid little guy walk strait into your feet, burning you last life? it is infuriating.other than that, another enemy is the hammer bros. the hammers always seem to hit you just when you seem to have everything under control.