The day of the old radio April Fool’s Day jokes seems to be all but done, although some stations still try them. With fake news such an issue and Internet trolling affecting elections, the pranks don't quite seem to have quite the same good humour that they used to. 

Still, the really good ones make headlines and become legendary. Like the old Spaghetti Tree Harvest done by the BBC in 1957. Or the classic “Metric Time,” that CFTR carried off in the mid 1970s (and which Dale Patterson’s Rockradioscrapbook highlights here.)

And don't forget Mike Cooper's infamous listener's attempt to assassinate him on April 1, 1976 that got the police involved and panicked some in the audience. Dale also has that bizarre audio here. 
 
I can’t say I’ve ever heard of most of the stunts outlined in the linked article below, but calling them the “best” seems a bit of a stretch. 
 
10 Best Radio Hoaxes You’ve Never Heard Before
 
My all time favourite April Fool’s moment wasn’t broadcast on April Fool’s Day and it wasn’t a joke. But it seems only appropriate to list it here just because it’s probably the most genuine and hilarious moment I think I’ve ever heard on radio. And none of it was planned.
 
It’s what happened when a one minute commercial wound up being stretched into a seven minute fit of uncontrollable laughter.
 
It took place in the 70s, when a host named Long John Nebel, a pioneer of the talk show format in New York City, was discussing various issues with a panel of experts, including a well known plastic surgeon and a marketing expert. At one point, he paused to read a live spot cold, using copy he never previewed. And that’s when he discovered it was an ad for a porno movie.
 
After that, all bets were off and after a slow start, the entire thing turns into bedlam. In fact, when he reaches the part in the spot (around 3:15) where they name the star of this filthy flick, I can honestly say I’ve never heard anyone lose it on air quite that much. And I doubt I ever will again.
 
For those who haven’t heard it, here’s that magnificent moment. For those who have, it’s worth another listen. I’ve replayed it dozens and dozens of times over the years, and it never fails to make me laugh. You’d have to be an April Fool not to.