On Monday, When Calls the Heart star Erin Krakow took to social media to wish her boyfriend and Hallmark Channel co-star Ben Rosenbaum a happy birthday ... and a very fun sense of humor ...

"I'm so proud of my tiny dancer. Happy birthday, big sister," Ben writes, as Erin replies in the comments, "4 years watching her grow into this little woman who already speaks like she's 14.

NASCAR star Ryan Blaney's sister Erin Blaney turned ... slides captured more of the fun, including a short video of her clapping and cheering after making her birthday wish. Her caption reflected ...