I bought a used Harley 45 Servicar for $100 when I was in college. I then managed to pick up 2 more Harley 45's that were not working. From the 3 bikes, I got 2 of them running. Then after a couple of years, I was down to only the servicar running. The trike had 3 forward gears and one reverse gear.
I had an old truck radio in the trunk and slung a 12" speaker from the handle bars. I used to pile 4 other guys on the trunk and go to the root beer stand - lots of fun when the car hop tried to figure out where to put the tray.
There were a bunch of us with motorcycles that used to go on beach parties. My 3 wheeler would hold six cases of beer in the trunk in addition to the radio.
Out of all the motorcycles I've owned over the years, that 3 wheeler was the most fun. If I could find something like that today, I'd buy it in a heart beat.
The pictures aren't very good, but the best I could find for something that old.