"You Ain't Seen Nothing Yet" is a song by Canadian rock band Bachman–Turner Overdrive (BTO). The song was written by Randy Bachman for the band's third studio album Not Fragile (1974). It was released as a single in 1974, with an instrumental track "Free Wheelin'" as the B-side. It reached the number one position on the Billboard Hot 100 singles chart and the Canadian RPM chart the week of November 9, 1974, as well as earning the band their only major hit single in the United Kingdom, peaking at number 2 on the UK Singles Chart.
"You Ain't Seen Nothing Yet" was written by Randy Bachman. According to Bachman, the song was performed as a joke for his brother, Gary, who had a stutter. They only intended to record it once with the stutter and send the only recording to Gary.

Bachman developed the song while recording BTO's third album, Not Fragile (1974). It began as an instrumental piece inspired by the rhythm guitar on Dave Mason's "Only You Know and I Know". Bachman 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. But when winding up production for the 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 Bachman, "what about the work track?" Bachman reluctantly mentioned that he had this ninth song, but did not 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."

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."