Folk duo Brewer & Shipley had a pretty big hit in 1971 with their song "One Toke Over The Line," a song that was clearly a reference to marijuana. That fact was lost on the wholesome folks at the Lawrence Welk Show, who had Dick Dale and longtime Welk show singer Gail Ferrell do the song as a duet. Apparently phrases like "Sweet Jesus" gave them the impression it was a spiritual song (which, in a stretch kind of way, I guess it could be) and Lawrence Welk even addressed it as such after their performance.
But really, in 1971 a lot of strangeness was happening, but fewer things were as strange as "One Toke Over The Line" being sung by these two so innocently on the show your grandparents (or maybe their grandparents) watched. In that sense, there's a certain charm to it. But the "WTF!" in the title of this YouTube recording of it is entirely accurate.
Enjoy, if you want to see something bizarre.