Get the latest from TODAY

Sign up for our newsletter
By Alyssa Newcomb

Jennifer Garner celebrated her birthday on Wednesday and her bestie Reese Witherspoon couldn't let the day slip by without posting a hilarious Instagram video toasting her pal and their "pretend babies."

"Happy birthday to my hilarious friend Jennifer Garner!" Witherspoon wrote. "Here’s to raising our glasses and pretend babies together. What should I name my burrito?"

The stars clearly think the baby speculation is hilarious. In the video, Garner, 47, and Witherspoon, 43, are drinking wine together, when Witherspoon says: "We really should not be drinking while we're pregnant!"

"Right!" Garner says. The two friends then jokingly rub each other's stomachs to feel their imaginary baby bumps. Witherspoon said her bump was "just a burrito," while Garner joked that hers was "the size of an avocado."

The inside joke between the A-listers appeared to start last month, when they were both on the cover of OK! Magazine, along with the headline: "Jen & Reese Baby Bombshells!"

There's a hilarious history of Instagram posts between the two actresses. When Witherspoon turned 43 on March 22, Garner dressed up in a marching band outfit and performed a birthday song for the "Legally Blonde" star.

"Many moons ago, my high school marching band played this song for homecoming. Today I play it for my boo, Reese Witherspoon," she wrote. "We have a groovy kind of love."