Put it right after the accusation in your edit, so the blame lands first and the denial answers it. Pair Ele Fez De Novo Incansável before it to set up the charge, then follow with Oi Meu Chapa for a casual reply that moves the scene on.
Sobre este som
This 2.6-second Portuguese voice clip has Cebolinha delivering his quick 'sei lá, eu é que não fui' denial in a small, sheepish voice. It feels playful and evasive, like a child caught in the act and trying to wriggle out of trouble with a shrug. The line comes from the Brazilian cartoon Turma da Mônica.