This word probably became popular due to the East Asia Power Resources(PWR) price uptrend caused by the takeover of Century Properties Inc.
Here is what Investopedia says:
A strategy of going public used by a company that fails to meet the criteria for listing on a stock exchange. To get onto the exchange, the company desiring to go public acquires an already listed company.
Century Property might have opted to be listed in the Philippine Stock Exchange and sees East Asia Power Resources as good way to be listed by Backdoor listing below is an excerpt from a disclosure submitted by PWR to the Exchange regarding the purchase of Century of PWR making it a wholly owned subsidiary.