Sped

A retarded; One who attends special classes. Also known as a "Tanner"

Jesus that kid's a sped.

No Balls

This is generally sued as a taunt, for example, if an individual doesn't want to do a dare, his companions might say "No Balls", to imply that if the individual didn't do the dare, he would have no balls; or he would have no bravery. It's essentially calling someone a pussy conditionally

Person 1: Nah dude I don't wanna do another blunt
Person 2: No balls, pussy.