What is a “hardened criminal”? A now-famous Viagra joke was posted on the newsgroup rec.humor.funny on May 20, 1998:
 
“Following the approval of Viagra by the UK’s health authorities, the first shipment arrived yesterday at Heathrow airport, but was hijacked on the way to the depot. Scotland Yard have warned the public to be on the lookout for a gang of hardened criminals.”
 
 
Wikipedia: Sildenafil 
Sildenafil, sold under the brand name Viagra among others, is a medication used to treat erectile dysfunction and pulmonary arterial hypertension. It is unclear if it is effective for treating sexual dysfunction in women. It is taken by mouth or injection into a vein. Onset is typically within 20 minutes and lasts for about 2 hours.
         
Google Groups: rec.humor.funny
Theft of Pfizer shipment
.(JavaScript must be enabled to view this email address)
5/20/98
London, 19th May.
Following the approval of Viagra by the UK’s health authorities, the first shipment arrived yesterday at Heathrow airport, but was hijacked on the way to the depot.
 
Scotland Yard have warned the public to be on the lookout for a gang of hardened criminals.
 
Newspapers.com
3 June 1998, Los Angeles (CA) Times, “Laugh Lines; Punch Lines,” pg. E-10, col. 2:
News Alert: Two men robbed a pharmacy of two years’ worth of Viagra. “Be on the lookout for these hardened criminals.” (Nicole Campbell)
 
Google Books
Laugh Twice and Call Me in the Morning
By Bruce Lansky
Minnetonka, MN: Meadowbrook Press
1999  
Pg. 47:
Did you hear about the three men who hijacked a truck full of Viagra ? The police are looking for a gang of hardened criminals.
 
Google Books
Playing with Words:
Humour in the English Language
By Barry J. Blake
London, UK: Equinox
2007    
Pg. 33:
In fact, there are probably as many Viagra jokes as there are unsolicited ads for the product on the internet. Examples include Use Viagra eye-drops to give you a hard look and Viagra stolen. Police seek hardened criminals.
 
Google Books 
Over the Hill and Lovin’ It
By Ed Fischer
Minnetonka, MN: Meadowbrook Press
2008
Pg. 98:
Did you hear about the three men who hijacked a truck full of Viagra? The police are looking for a gang of hardened criminals. - Anonymous
 
Twitter 
Al Snow
@TheRealAlSnow
Breaking News : A Viagra shipment was stolen today and cops are on the lookout for a gang of hardened criminals
5:10 PM · Sep 27, 2017·Hootsuite
 
Twitter 
PharmaFactz
@PharmaFactz
A pharmaceutical truck full of Viagra was stolen today.
Police are asking the public to keep an eye out for any hardened criminals.
1:16 PM · Feb 13, 2020·Twitter for Android