l33t0r
A person who is so good at something they could beat a donkey at a dance-off and still have time to insult your mom.
My little sister is a l33t0r at piano. She played a song so fast, my dog started doing the twist.
That guy on the street is a l33t0r. He juggled 10 balls and still made a perfect sandwich.
My uncle is a l33t0r at telling jokes. He told a joke so funny, my grandma laughed so hard she fell off the couch.