From Wikipedia:
You Ain't Seen Nothing Yet" was written by Randy Bachman. In The Rolling Stone Record Guide, writer Dave Marsh called the song "a direct steal from The Who," but "an imaginative one." [ 1 ] The chords of the chorus riff are very similar to the ones used by The Who in their song "Baba O'Riley," and also, the stuttering vocal is indeed reminiscent of "My Generation." Randy insists that the song was performed as a joke for his brother, Gary, with no intention of sounding like "My Generation." [ 2 ] Gary had a stutter, and Randy only intended to record it once with the stutter and send the only recording to Gary.
Randy developed the song while recording BTO's third album, Not Fragile. It began as an instrumental piece inspired by the rhythm guitar of Dave Mason. Randy says "it was basically just an instrumental and I was fooling around... I wrote the lyrics, out of the blue, and stuttered them through." The band typically used the song as a "work track" in the studio to get the amplifiers and microphones set properly. [ 3 ]
But when winding up production for their second album, Charlie Fach of Mercury Records said the eight tracks they had lacked the "magic" that would make a hit single. Some band members asked Randy, "what about the work track?" Randy reluctantly mentioned that he had this ninth song, but didn't intend to use it on a record. He said, "We have this one song, but it's a joke. I'm laughing at the end. I sang it on the first take. It's sharp, it's flat, I'm stuttering to do this thing for my brother." [ 2 ]
Fach asked to hear it, and they played the recording for him. Fach smiled and said "That's the track. It's got a brightness to it. It kind of floats a foot higher than the other songs when you listen to it." [ 2 ]
Bachman agreed to include the song, but only if he could re-record the vocals first, without the stutter. Fach agreed, but Bachman says "I tried to sing it normal, but I sounded like Frank Sinatra. It didn't fit." Fach said to leave it as it was, with the stutter. [ 2 ]
It is said that Gary Bachman has since lost his stutter.
Well, i almost had it right.