This word is the superlative form of the word cutest. Usually used to describe a person that is unbelievably cute. There is no higher form of the word cute than this.
adjective /ˈkju tɪstɪst/ (informal, hyperbolic, non-standard)
1. Denoting the utmost conceivable degree of cuteness; used humorously or emphatically to describe a person, animal, or thing perceived as surpassing all others in charm, endearment, or visual appeal.
Word used win in a 'cute war' (different word, different definition). Used to tell someone that they are cute. The steps of cute are now. Cute, Cuter, Cutest, Cuterest. So no you dont have to stop the argument early. But yes, it will end with this word. Usually used when a guy wants to make a girl blush more than twice. If hes only seen her blush twice, ofcourse.
"hannah, you are so cute." "No your cuter." "No!! Your cuterest!!! called it.