Watch now: Carrie Underwood sings a helium-fueled "Happy Birthday" for four-year-old Isaiah

ABC/Mark LevineYou probably shouldn’t try this at home, but it’s fun to listen to: For her son’s birthday, Carrie Underwood treated him to a helium-fueled serenade.

Isaiah Fisher turned four on Wednesday, and late in the day, his dad Mike Fisher shared an Instagram video of Carrie doing an unforgettable version of “Happy Birthday.”

In the clip, Carrie’s seated in a chair — dressed all in black — while holding her and Mike’s newborn and draining the helium from a yellow balloon. Isaiah’s little brother Jacob was born five weeks ago.

The birthday boy is seated opposite his mother, hanging on her every word.

“Happy birthday to you/Happy birthday to you,” Carrie sings in an incredibly high soprano, as Isaiah erupts in laughter. She also adds an impossible trill on the end of “Happy birthday, dear Isaiah.” By the end, he can’t wait to try it himself.

You can check out Carrie’s birthday song on Instagram. Earlier in the week, she shared a photo of Isaiah’s impressive Kermit-the-Frog-inspired Muppets Most Wanted cake.