look up any word, like dirty sanchez:
The word 'Beyn' orginated from Hinde House Secondary School, it was first referred to as 'Bean', and after constant used it evolved to 'Beyn'. The word is commonly used when someone does or says something stupid or maybe says something weird, stuff along those lines, and therefore they're called a 'Beyn'.
"You beyn"

Guy says, "I listen to Westlife they're awesome", other guy says, "You beyn"
by allstardude November 14, 2010