Meanwhile, Lowndes posted a pic showing a hand wearing an engagement ring.
As it turns out, the snaps were simply a ruse to promote Lowndes' new music video, "Déjà Vu (Remix)." The NSFW video features Lovitz as a delusional sugar daddy, as Lowndes strips down to various stages of undress.
"I couldn't get over the amount of people and close friends who thought I was for real," Lowndes told ET. "My business manager asked if we should insure the ring!"
But Lowndes revealed that the ring wasn't even hers.
"It was a picture from Google," she explained.
The 90210 star took full responsibility for the prank, which was nearly a year in the making.
"I love playing practical jokes, so last year on April Fools' Day, it leaked I was in Will Ferrell's Lifetime movie [A Deadly Adoption], so this year, I decided to pull an April Fools' joke of my own, and what better partner in crime?" she said.
Lovitz and Lowndes became friends after meeting on the set of the TV show, Hawaii Five-0. While their relationship might be just platonic, Lovitz assured us that it isn't totally out of the realm of possibility that he could be linked to a 27-year-old starlet.
"Younger women like me!" Lovitz said. "I was taught to speak funny and have a big stick, and it works."