Sterile Jokes

A doctor had just delivered twins. They were a boy and a girl.
The head nurse brought them out for their father to see.
He could hardly believe his good fortune. The girl baby had a pink blanket wrapped around her and the boy baby was enclosed in a blue blanket. He took one step forward just so he could touch the babies and believe they had finally arrived.
As he started to touch them the nurse took a step backwards and said, "You can't touch those babies. You aren't sterile!"
With out missing a beat, he retorted "You're telling ME I'm not sterile?!"

A doctor had just delivered twins. They were a boy and a girl. The head nurse brought them out for their father to see. He could hardly believe his good fortune. The girl baby had a pink blanket wrapped around her and the boy baby was enclosed in a blue blanket. He took one step forward just so he could touch the babies and believe they had finally arrived. As he started to touch them the nurse took a step backwards and said, "You can`t touch those babies. You aren`t sterile!" With out missing a beat, he retorted "You`re telling ME I`m not sterile?!"

A doctor had just delivered twins. They were a boy and a girl.
The head nurse brought them out for their father to see.
He could hardly believe his good fortune. The girl baby had a pink blanket wrapped around her and the boy baby was enclosed in a blue blanket. He took one step forward just so he could touch the babies and believe they had finally arrived.
As he started to touch them the nurse took a step backwards and said, "You can't touch those babies. You aren't sterile!"
With out missing a beat, he retorted "You're telling ME I'm not sterile?!"

Why do they use sterile needles for lethal injections?