A donkey for a trade
A donkey for a trade means you got a way better deal than you expected. It's like getting a goldfish for your birthday instead of a lousy old sock.
Your friend said, 'You got a donkey for a trade.' after you told him you got a scholarship to a fancy school.
Your teacher said, 'You got a donkey for a trade.' after you told her you joined a band.
Your mom said, 'You got a donkey for a trade.' because you dated a famous singer.