Kim Kardashian's BFF -- I Hope Her Baby Has a Big Head

Kim Kardashian's new baby girl is gonna have a HUGE HEAD ... just like her superstar dad Kanye West ... so says Kim K's BFF Jonathan Cheban.

Jonathan -- who pops in and out of various Kardashian reality shows -- was out in LA last night just hours after Kim K gave birth and our photog asked the question on everyone's mind ... will baby Kimye end up with a giant Kanye-sized melon?

For anyone who knows who Kanye West is ... that question has two possible meanings (think about it). Got it. Good.

The crazy part is ... Jonathan actually answered the question -- and it's pretty great.

Now, here's Kanye's head in action ...