Gigi Hadid -- Birthday Bikini Shoot ... Aw, You Shouldn't Have! (PHOTOS)

B'Day Bikini Shoot

... Aw, You Shouldn't Have!

Gigi Hadid does not know how birthdays work -- instead of receiving gifts, she's giving them ... in the form of a hot new swimsuit photo shoot. Yes, it's a happy birthday ... for us all!

Hadid celebrated her 20th on Thursday by posing for a bunch of photos in Miami and, thankfully ... changing into a bunch of colorful and revealing swimsuits in the process. 

If every day could be just like Christmas Gigi's birthday ... what a wonderful world this would be.