A speedball is a powerful and dangerous drug made by mixing cocaine and heroin.
Speedballs are very bad and can hurt people.
Examples:
He took a speedball and got very sick.
Speedballs are not safe to use.
The doctor said that taking speedballs is very dangerous.
I heard that some people think taking speedballs is a good idea, but it's not.
Taking speedballs can be deadly.
Speedballs are never a good choice.