The Gossip Girl hunk's younger sibling Candice became a first-time mum to a son named Hawkins in early April (12) and Crawford was by her side to witness the birth of his nephew.
The TV star admits it was an unbelievable experience, telling People.com, "It's an extremely bizarre, beautiful process. I'm not going to give you all the intimate details of my sister having a baby, but it was absolutely incredible... There were a lot of pictures flying around, that's for sure."
And Crawford has been spoiling the tot since day one: "I am the best uncle. I'm like Christmas vacation. I'm the best."
Candice Crawford wed Jessica Simpson's ex-boyfriend, American footballer Tony Romo, last May (11).