She just made up any old excuse.
She's been moaning about wanting to leave for the past 3 days,
so she nominated the two who she thinks are the most popular.
Her logic being that if she's up against them, then surely she'll go.
That's why she cheered when her name was announced
and why she said "I hope it's Charlotte" when BB said "and the next person up for eviction is..."
She just made up some stupid excuse about them both farting, that's all. Don't look any deeper into it than that.
Charlotte, Carol & Courtney all like each other and get along just fine.