“Right back at you.”
You and a friend show up to a party wearing the exact same shirt. He laughs and says "Nice shirt!" You reply like this.
Right back at you.
This phrase means "you too". You can use it when someone compliments you.
A: Nice car!
B: Right back at you.
People who use this phrase sound fun, sporty, and easy-going. It might make you sound a little "slick" (too smooth) like a salesperson.