Garrison Keillor is the host of a program on Minnesota Public Radio about a small, fictional town called Lake Wobegon. The town is so small that people lock their car doors only in July during the zucchini harvest—to prevent others from adding a bag of zucchini to the front seat. Keillor has told the anecdote over many summers.
 
“Garrison Keillor (see http://phc.mpr.org/about.shtml) has a perennial joke about having to lock one’s car in the summer, or else someone will leave zucchini inside” was cited in print in 2001. The Keillor anecdote is frequently brought up in articles about zucchini.
     
 
Wikipedia: Garrison Keillor
Gary Edward “Garrison” Keillor (born August 7, 1942) is an American author, storyteller, humorist, and radio personality. He is known as host of the Minnesota Public Radio show A Prairie Home Companion (also known as Garrison Keillor’s Radio Show on United Kingdom’s BBC Radio 4 Extra, as well as on RTÉ in Ireland, Australia’s ABC, and Radio New Zealand National in New Zealand).
     
Google Groups: alt.fan.pratchett
[R] TT changes: editor or typo?
Laurabelle
2/17/01
Vegetables, was TT changes: editor or typo?
On 16 Feb 2001 04:50:35 GMT, .(JavaScript must be enabled to view this email address) (Christin
Keck) wrote:

>Zucchini are common as dirt here. In fact, they are a gardening joke,
>because they grow so very very well. Once you plant one, you cannot
>get rid of them, and you can only eat so much zucchini bread before
>they institutionalize you for killing all your neighbors who keep
>growing them and giving them to you.
 
Garrison Keillor (see http://phc.mpr.org/about.shtml) has a perennial joke about having to lock one’s car in the summer, or else someone will leave zucchini inside.  The horror, the horror!
 
(It’s funnier when he says it.)
 
GOogle Groups: rec.gardens.edible
days on seed pak
Jan Flora
6/12/03
(...)
(Garrison Keillor says people in MN lock their car doors when they go downtown in the summertime, so people won’t leave bags of zucchini on the back seat.)
   
yes! magazine
HAPPINESS
My Year of Eating Local: Zucchini Wars
by Barbara Kingsolver
posted Jul 26, 2007
(...)
Garrison Keillor says July is the only time of year when country people lock our cars in the church parking lot, so people won’t put squash on the front seat. I used to think that was a joke.
   
the kitchn
July 23, 2012
Beyond Zucchini Bread
“If you want zucchini” says Garrison Keillor, in his drawling reminiscence of Lake Wobegon, the quintessential Midwest town too real to be real, “just go to church on Sunday. You’ll have all you can handle.” People in garden-minded towns should lock their car doors, this time of year, or else they may find a large, moist sack of green monsters on their back seat
     
Tips from Ashton Ritchie   
Got a Suggestion for Your Extra Zucchini… And it’s Not What You Think
July 25, 2012
Garrison Keillor once said the only time Lutherans in Lake Wobegon lock their car doors in the church parking lot is in summer. Otherwise they are likely to come out of Sunday service to find that someone has left a grocery bag full of zucchinis on their front car seat.
 
Green Door magazine (Catskills & Hudson Valley, NY)
Buying Time
Published In:
Summer 2013 - Vol 3 No 2
(...)
“Why do the inhabitants of Lake Wobegon lock their cars in the month of August? So their neighbors won’t leave bags of zucchini on the back seat,” jests Garrison Keillor. Sort of.
 
The Day (CT)
A Fox in the Blueberries and Other Garden Surprises
By Steve Fagin
Published August 01. 2014 11:17AM   Updated August 01. 2014 11:21AM
(...)
The old joke is that in small towns the only time people lock their car doors is during the zucchini harvest.