123rf

I'll eat my hat.
= I'll be very surprised. (used to express strong disbelief)

If you quit smoking, I'll eat my hat.
She's never on time. If she's on time today, I'll eat my hat.

Don't flatter yourself.
=Don't overestimate your own importance.

Don't flatter yourself. You're not so important as you pretend to be.
Don't flatter yourself. You're just at the beginning.

By Chun Sung-woo (swchun@heraldcorp.com)