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Gfactor, General Questions Moderator
Ooh, that’s quite a mashup. My local one plays nothing but Christmas carols.
This is the song my ice cream truck usually plays.
When I was a kid, the tune was Greensleeves. The van that does the same area these days plays The Teddy Bears’ Picnic. That’s yer actual dumbing down right there. 
I’ve also heard vans playing The Entertainer.
Ours plays “Greensleeves”, although we don’t see it very often round our way. Too few kids to make it worthwhile, but they probably make a killing every weekend in the park round the corner.
I’ve heard ice cream trucks use Greensleeves here in California, too, as well as most of the other tunes mentioned so far, plus “Sailing, Sailing, Over the Bounding Main” (also known as “Sinbad the Sailor”). I no longer get the trucks in my (predominantly hispanic)neighborhood, though–just handcarts with incredibly piercing bells manually tinkled (probably by a guy named Manuel).
The few times I’ve seen a mobile ice cream stand in Spain, it was a van that had been planted in place for the duration - it didn’t move. And unless it was part of a fair (in which case it would play whichever songs were competing for the title of “Song of the Summer”) it wouldn’t play music.
That’s the only song I can remember my neighborhood ice cream truck playing.
When I was a wee lad, ice cream treats were dealt from specialized tricycles with a huge cooler between the front wheels. The popscicle monger dingled a brass bell as he rode.
When the trucks took over, the tune was always a calliope rendition of either Stars and Stripes Forever or the circus classic Over the Waves. Later, we’d hear When The Merry-Go-Round Broke Down or Turkey In The Straw, but still on a calliope.
I once asked a driver how he could stand to hear the same tune all day, every day. He said, with all the refrigeration in the truck, he couldn’t hear the music at all.
At the State Fair, I heard the calliope wagon from Indiana University. Holy Moo Cow, that’s loud! I mean, it’s Grateful Dead loud. The player, atop the wagon, wore serious protective earmuffs.
Ours plays The Entertainer or Did You Ever Know a Lassie (the tune is also known as The More We Get Together). It took me weeks to figure it out–I haven’t heard that lassie song since I was one! (mom was into folk tunes).
The Godfather? How twisted is that?
I’ve also heard Music Box Dancer–seems a fitting role for a tune that was burned into my brain as a teen.
I hear the tune from The Third Man quite often. I also hear You are my Sunshine a lot, probably because the tune’s been used for football crowd songs for a few years.
There’s trucks here in Chicago that use a series of various sound effects, followed by a “Hey!” which-- stupid, stupid me-- always makes me look. I don’t even really hear or pay attention to the sound effects til I hear the person yelling “Hey!”
Round here it’s the nursery rhyme “Girls and boys come out to play”
Of course smart parents tell their kids the icecream man only plays the tune to show that he’s run out of icecream
Is this followed by a man in a chili truck?
When I was a kid, I think it was London Bridge.
The trucks that go through my neighborhood in Washington State play either Pop Goes the Weasal or Greensleeves. And, speaking as a day sleeper, those are both REALLY ANNOYING.
Oh, wait, wait! It was Pop Goes the Weasel. Thank you. 
My neighborhood gets the “Music Box Dancer” truck, the “Sailing, Sailing” truck, 2 “Pop Goes the Weasel” trucks, and one that plays several tunes including “Happy Birthday to You.” In addition, while most of the trucks around here sell Good Humor-type treats as well as chips and canned soda, one of the “Pop Goes the Weasel” trucks sells soft-serve ice cream and small bags of Fritos with a spoonful or two of chili dumped right into the bag. It’s an embarrassment of riches, let me tell ya.
Ours does, too.
When I first moved to Troy, NY, I went out for a few…okay, WAY too many drinks with my roommate and woke up at noon to the sound of “The Entertainer” really fucking loud!
I jumped up out of bed and was in a still-drunken stupor, stumbling around the room like a dog looking for his tail. I couldn’t figure out where the music was coming from for a couple of minutes. Then I saw the friggin’ truck and went back to bed.
For a couple of minutes, I had never been so confused in my life. Where I’m from, we didn’t have ice cream trucks.
All I’ve ever heard in the southern US (Texas, Georgia, Florida) was *Pop Goes The Weasel. *
Just what, may I ask, would be wrong with Freebird? I’d love to see an ice cream truck drive by with all the kids on the sidewalk holding their lighters in the air.