Updated

A mom desperate to help her daughter become prom queen went to extraordinary lengths -- renting a roadside billboard to promote her campaign.

The towering, bright pint billboard showed a picture of the 18-year-old high school senior from Killeen, Texas, along with the call to arms, "VOTE Brandy Day for Prom Queen."

It was located outside Day's Harker Heights High School, KXXV-TV reported.

But the bid backfired, with Day teased at school over the audacious advertising -- which failed to land her the crown.

Her mother, Tammy Day, defended the billboard, telling ABC News, "They may consider it overboard, but I don't look at it like that. I look at it like it's a once-in-a-lifetime opportunity to make memories ... This is her last prom. She's never going to be in high school again and I wanted her to have the best moment possible during her last school year."

During her bid to become prom queen, Day had joked about hiring a billboard, and her mom decided to do just that.

The older Day said of the billboard and resulting teasing, "She's shocked. She's speechless. I don't think she really knows what to think. But I know she's happy because she worked hard."

Despite missing out on being a prom queen finalist, Day was still looking forward to marking the end of her high school years at the dance, before heading to Baylor University to study pediatrics, her mom said.