The phrase não achei graça is everyday Brazilian Portuguese for saying something was not funny, and its popularity as a sound comes from how instantly understood that reaction is online. Short voice clips of common expressions spread easily through WhatsApp groups, meme pages and short videos, where users reuse them as ready made responses. This one survives because it fits so many situations, from friendly teasing among friends to commenting on a joke that tried too hard, without needing any extra explanation.