"Oh... never mind" -- Fry quote?

Hi! I am trying to track down something to use as a video clip. I'm pretty sure I've seen an episode of an animated series wherein a character, trying to warn people only to see that they are too late to stop something from happening, just dejectedly says, "Oh... never mind."

I kinda picture this being done by Fry, so I was hoping someone could say if I'm right or not, and if the former, what episode was this? Thanks!