The deal took place on O'Connell Street
Potentially lethal drugs are easily sourced from dealers online who are selling to users in Dublin city centre under the nose of gardai.
A special investigation by the Herald has uncovered how within 24 hours of enquiring through Facebook where to buy drugs, a dealer is hand-delivering them on O'Connell Street.
Where once young Irish teens had to have a personal link to a dealer - limiting their access to drugs - they now have access to dozens of potential sources over the internet.
Drugs including cannabis, ecstasy, cocaine and so-called party pills are all openly being marketed on social media.
Security sources have claimed that dealers are increasingly taking advantage of social media and other websites to sell their products and avoid detection by gardai.
Gardai believe a batch of potentially lethal ecstasy tablets, called Green Apple and Green Rolex, which caused a series of hospitalisations in 2014 were bought online.
After logging on to a Facebook page which discussed drug use in Ireland, the Herald asked a number of users where drugs could be bought in the city centre.
One Facebook user pointed out an ad on a popular sales website. The website was openly offering "pollen" for sale.
Pollen is one of the strongest and most expensive types of cannabis resin for sale in Dublin.
The ad read: "Lovely fresh pollen available city centre €50 a q. 100pc genuine and face to face meet no bulls**t no time wasters please."
After a quick exchange of emails, the dealer - who used the name "Colm" - sent his mobile number and offered to meet the next day to sell us an ounce of cannabis (28 grams) for €180.
He wrote: "let me know I'm around city centre. Before 2pm and I'll do an oz for €180.
"Meet me at the GPO at 2pm."
The following day at the meeting point a garda van (above) was parked just metres away in the centre of O'Connell Street.
On his mobile phone, the dealer was undeterred and said: "Just walk towards the statute."
After meeting, the dealer then pointed towards the road behind the closed Clerys department store, saying: "We can walk down the lane over there."
Colm said he had been selling cannabis over Christmas period to make extra cash.
"I have it there every second or third week, I get a little bit in.
"It's in the bag there pal, walk down there. There's 28 (grams) in there."
He claimed he was looking to sell off his last ounce.
"It's a bit [dodgy] meeting f**kers over the internet. You don't know who's who."
The cannabis was never purchased. Cannabis is not the only drug being sold online.
Drugs are still being openly sold on another popular website, which also hosts a series of "adult ads".
One dealer - who uses the moniker "Charlie Sheen" - emails out a weekly product and price list to his customers.
Last month, he wrote: "Added to stock 3mmc and weed cheese strain …out of stock mdma, ket, upjohn…coming soon flake coke, ket, d10, upjohn90, diclazepam."
In one recent post, a dealer was offering to sell prescription drugs straight from the packet.
Ray McAdam, a Fine Gael Councillor for north inner city, said that the easy accessibility of drugs would be a huge source of anxiety for parents.
"The fact that you can pre-order your drug choice, akin to ordering a takeaway meal, is extremely worrying. That is why I want to see the National Drug Squad tackling the availability of these drugs, and making sure that social media companies are working closely with the gardai to stamp this activity out."