To hit someone with an open hand, especially on the buttocks.
This is usually done as a punishment, especially for children.
Examples:
Dad skelps me when I'm naughty.
She skelps her brother for being mean.
He skelps the ball with his hand.
The wind skelps my face when I'm outside.
The giant skelps the dragon with his hand.
The teacher skelps the desk to get the students' attention.