Mischievously Mine by Leigh W. Stuart

Only one can come out on top…
Sandra Kelly has a take-no-prisoners policy when reporting the local news—and for getting what she deserves. For instance, first place in the Townsperson of Year contest, and a promotion at the station. Except, one man stands in her way.
Cooper Hall needs to win the upcoming Townsperson contest for reasons of his own—and a certain sexy journalist won’t stop him. No prank is too complicated, no scheme too elaborate, and her red lace panties will not distract him. Much.
They signed a peace treaty years ago and swore they’d never speak of the pranks again. But when they both set their eyes on the same prize, their prank war rekindles. This time, they aren’t stopping at tighty-whities on flag poles and stuffed tarantulas, either. Love has no place in war, and these two enemies play to win.