There is a lot of debate on whether or not you can subconsciously pick up an accent. Some people believe that it is possible to absorb the sounds and patterns of a new language without realizing it, while others contend that this phenomenon does not exist. The truth likely lies somewhere in between. It is probably possible to unconsciously mimic the sounds of a new language if you are exposed to it for extended periods of time, but it is unlikely that you would be able to achieve native-level fluency without actively trying to learn the language.