Ken as Barbie's Boyfriend

When I introduce myself in the US, I often say, "My name is Ken, like Barbie's boyfriend." Crowds laugh at my joke.

Six month ago, when I used this joke for the first time, I didn't understand what it means. Since I came to the US, six month has passed. Recently I think I understand. It is related not to the English language but the culture in the US. Maybe, I cannot understand it perfectly because I didn't grew up in the US with Barbie's staffs. (Maybe, even if I grew up in the US, I would haven't played with Barbie's staffs...) Anyway, though I cannot understand it perfectly, I can imagine sense, feel and share it, and therefore I can understand the US more. That's what I want.