"Jesus! JEEZ. Oh m' word."
Skip ahead to 1:38 for the big bang. Or don't. Waiting it out adds a particular flavor of nervous anticipation that makes the whole thing that much more exciting. I love Dad's breathless excitement at the beginning... and his flabergastedness when it blows up—literally—in his face. Also his son's toldya so at the end of the clip rounds out the whole rocketfail rather nicely.
Update: Further review, and the help of a few commenters, has led me to conclude that it is in fact the dad saying "I tried to tell you," and not the son, as was the original interpretation.