Boyfriend Dresses in Panther Mascot Suit at 'School Assembly' to Propose to School Principal

He'd been planning the proposal since Christmas.

Principal Mandy Vasek wasn't expecting the best moment of her life to happen at a Texas elementary school assembly.

Vasek’s boyfriend, Russ Johnson, had been planning the fake assembly at Castleman Creek Elementary School along with a small number of Vasek’s colleagues since before Christmas, knowing he wanted to propose on January 26, their one-year anniversary.

Read: Newborn Surprises Mom by Wearing Onesie With Proposal: 'Mommy, Will You Marry My Daddy?'

On the day of the assembly, Vasek’s boss called her into a meeting.

In the meantime, Johnson donned the school’s mascot outfit before Vasek came into the assembly of 600 students and gave the announcements as usual.

“While they were having the meeting I was getting into the panther costume and letting the cheerleaders know why they were really there because they didn’t know,” Johnson told InsideEdition.com.

In a moment captured on camera, the cheerleading squad began to chant the words, “Will you marry me?”

It was then that Johnson whipped off the head of the panther mascot costume and got down on one knee amid the screams of all the kids.

And she said yes.

Vasek said she was shocked to find out the whole performance was a front for Johnson's proposal.

“I had received an email from the cheer coach from the high school," Vasek said. "She mentioned having the girls perform for the school before an upcoming competition as well and I didn’t think anything of it."

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“It’s definitely something we have been talking about for a while but I was not expecting it that day,” Vasek said. “I had no idea he was in the mascot costume and then he took the face mask off and I realize he was there and it was true and he was going to ask me to marry him. It was the best moment of my life.”

The two are planning their wedding for St. Patrick’s Day.

Watch: Man Who Met Future Wife in Kindergarten Re-Creates Ad for Surprise Proposal