'Now I Know Why Girls Need A Sports Bra' Caitlyn Jenner

Caitlyn Jenner proved she can have a giggle as she gets used to the changes in her body, in a new teaser clip for her reality show, I Am Cait. 

Dressed in tennis whites, the 65-year-old star, formerly Bruce Jenner says, 'Now I know why girls need a sports bra,' as she struggles to contain her 36D surgically enhanced assets. 

Talking about adjusting to her new life, the reality star says, 'I have a lot to learn,' adding, 'all of a sudden, I am the authority on hair and make-up.'