What do you mean you don't know what 'cosplay' is? Dear oh dear, you really are out of touch. Lucky for you, the country's foremost authority* on the psychology of cosplay isn't far away, as you'll see from the clip below:
*Truth be told, I'd never heard of cosplay either until the students making this short film got in touch asking for a psychologist's take on it. Hey, I didn't want to let them down, did I?