That bizarre poem read by Shia LaBeouf at the 2015 Grammys? Us Weekly can exclusively reveal that it was a love letter read on behalf of her husband Erik Anders Lang. Credit: Kevin Winter/WireImage

So ridiculously romantic! Just before Kristen Wiig and Maddie Ziegler performed on behalf of Sia at the 57th Annual Grammy Awards, Shia LaBeouf's bizarre and poetic introduction was delivered in lieu of the singer's husband Erik Anders Lang, a source reveals exclusively to Us Weekly.

"What Shia read to introduce Sia wasn't actually a poem," the source tells Us. "It was a love letter from Sia's husband!"

The introduction was considered bizarre — i.e. typical LaBeouf behavior — by many viewers unaware of the full context.

"For Sia: I feel like this may be strange to say this here," LaBeouf said on behalf of Lang. "I love you so. Punch me if I stop crying. I raised a white flag for you, defeated finally. If strength were made of broken pieces, you and I would always win. It is, though, and building and statues wink at us. I could squeeze you to zero. I’ll never know another. What am I going to do? Punch me if I stop crying, and I’ll do the same. Love, Erik."

The insider tells Us that LaBeouf — who starred in Sia's "Elastic Heart" music video — secretly worked with Lang to pull off the surprise. "Erik and Shia conspired together and did this as a gift to Sia," the source adds. "She was COMPLETELY surprised and had no idea."

The "Chandelier” singer-songwriter married filmmaker Lang last August at her property in Palm Springs, Calif.

Sia's reaction to her husband's romantic gesture, however, remains a mystery as she faced a wall throughout the entire performance of her smash single at the Staples Center on Sunday.