Oi Guilherme circulates online as a short named greeting clip, shared mainly through WhatsApp style voice notes and soundboards where brief Portuguese callouts are reused as jokes. Its exact original recording and speaker are not widely documented, so its spread is tied to how it is used rather than a known show or film. Creators save it for any moment a Guilherme is introduced, tagged, or spotted, turning a personal hello into a running gag. The specificity of the name keeps it popular in Brazilian and Portuguese speaking communities and in friend groups with their own Guilherme.