Garantirai
Garantirai is not a standard dictionary form in Portuguese or other widely used languages. In Portuguese, the verb garantir (to guarantee) is conjugated in the future indicative first person singular as garantirei. Therefore, garantirai is typically seen as a misspelling or as a stylized form rather than a correct grammatical form.
Because it does not correspond to a formal conjugation, garantirai is occasionally used as a coined term
If garanted as a brand name or project title, Garantirai would be interpreted through its branding context
See also: garanti a, garantia, garantidor, garantias. Notes: the correct ordinary conjugation for the first person