's son Luca Cruz is becoming quite the celebrity.
Duff has already shared pictures of her little guy looking angry
, and he never fails to be 100% adorable. In the latest shot, the 3-month-old is simply hamming it up for the cameras while on the beach with his mom.
Duff has been vacationing in Mexico
with Luca – and judging by her recent Tweets, has been having a great time.
"Ahh all tucked in, baby down :)," she Tweeted late Thursday night. "Such a great trip with my favorite people [Haylie Duff] my mommy and LUCA! Goodnight tweet hearts. My eyes are closing."
Duff has also been working on her bikini body
, saying in April that "there is a little bit of pressure" on her to lose weight.