A shortened version of "Freakin Idiot". You normally say it in a really retarded or high-pitched voice. You can also say it like freh eh! OR fruggin idjiot! It all started because some guy would always say freakin idiot really ugly so his friends started making fun of him. Now he does it on purpose.
I actually don't even know the guy, my friend does. But yeah; just do it. It's fun. :D
"Dude, I think I ran over your dog."
..
"FRUH UH!! That's my sister!"
And dying in yo' bed many years from now, would ya be willing ta trade all da days from dis here day ta dat fo' one chance, just one chance, ta come back here as young men an' tell our enemies dat dey may take our lives but dey will never take our freedom ... YUB NUB!