"Hey, can you tell my voice from a ten-year-old? Ay caramba!"
The 10 year old voiced man' is a man who sounds like 10 year old Bart Simpson.
He was a construction foreman in Springfield. After the student body was out of school due to a massive teacher's strike, Bart visited a construction lot and played his usual mischief, namely by using a megaphone and telling a crane operator to spin the crane real fast (which he did and was implied to have broken the crane off due to velocity), as well as telling a sand dumper to dump three tons of sand onto the Porta-potty. The Foreman busts Bart and snatches away the megaphone, for him to angrily ask how they could mistake his voice for a ten-year-old kid's voice and exasperatedly says to himself, "Ay Caramba."