「やられたらやり返(かえ）す。倍（ばい）返（がえ）しだ！」　
"If your enemies hurt you, take double the payback!"

This is a signature phrase that a hero used in Japanese TV drama, "半沢直樹（Hanzawa Naoki）", which was broadcast during this summer.
"半沢直樹（Hanzawa Naoki） " was hugely popular achieving an average audience rating of 28.7% and 42.2% for the last episode.
Since you can look into the information of the TV program for yourself, I want to put it on the back burner and focus on what is happening now in Japan. 

Not only is it getting record-breaking audience rates, the drama is also having a big effect on our lives. 
"倍（ばい）返（がえ）し（Take double the payback）" has become a vogue phrase now; you can find it on twitter or Facebook everyday in Japan.
You can also find "倍返しセール（2 times return sale）" on many advertisements.
Because the hero also said "10倍返し（take 10 times the payback）" in some episodes, the word " 10倍返し（take 10 times the payback）" is often used too.

One of the most time-honored department stores Matsuya-Ginza uncovered their 福袋（ふくぶくろ）; "lucky bags" or "mystery bags" for the beginning of next year.
福袋 are one of the Japanese New Year's Day customs where merchants make bags filled with unknown random contents.
They usually contains goods that are much more valuable than the price of the bags. 

Reportedly Matsuya-Ginza department will sell 10倍返し福袋; 10 times 88,000 yen lucky bags which contain fur coats worth 880,000 yen!! 
(I wonder if we can still call it a 福袋 even though we know the contents.)

The buzzword is easy to use in many situations, so please use it with your Japanese friends.
They may be pleased to know you are familiar with the present Japanese culture.
It will be a good topic of conversation.

半沢直樹(Hanzawa Naoki) official HP