To guarantee that something is true, that it will definitely happen; that it is what it is and you shouldn't doubt it.
Danny: "bro, are you sure she's coming to the dance with you?"
Brandon: "yeah, sharon just texted me– she said she guarandamnteed she'd be here, just running a little bit late."
Brandon: "yeah, sharon just texted me– she said she guarandamnteed she'd be here, just running a little bit late."
by mercury_frappe January 05, 2017