Jeffy is the adopted son character from SML, the YouTube sketch series created by Logan Thirtyacre, where puppet versions of Mario characters get into crude, chaotic stories. Jeffy became the breakout star for his helmet, pencil in his nose, and blunt one liners that fans clip into soundboards. This up your ass line spread through YouTube edits, TikTok reposts, and Discord servers as a quick insult effect. Its short length and instantly recognizable voice keep it in rotation long after the original sketch.